Total Complexity | 147 |
Total Lines | 1185 |
Duplicated Lines | 2.36 % |
Coverage | 0% |
Changes | 0 |
Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like openscap_report.dataclasses often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
1 | import re |
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2 | import sys |
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3 | import copy |
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4 | import types |
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5 | import inspect |
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6 | import keyword |
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7 | |||
8 | __all__ = ['dataclass', |
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9 | 'field', |
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10 | 'Field', |
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11 | 'FrozenInstanceError', |
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12 | 'InitVar', |
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13 | 'MISSING', |
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14 | |||
15 | # Helper functions. |
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16 | 'fields', |
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17 | 'asdict', |
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18 | 'astuple', |
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19 | 'make_dataclass', |
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20 | 'replace', |
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21 | 'is_dataclass', |
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22 | ] |
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23 | |||
24 | # Conditions for adding methods. The boxes indicate what action the |
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25 | # dataclass decorator takes. For all of these tables, when I talk |
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26 | # about init=, repr=, eq=, order=, unsafe_hash=, or frozen=, I'm |
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27 | # referring to the arguments to the @dataclass decorator. When |
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28 | # checking if a dunder method already exists, I mean check for an |
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29 | # entry in the class's __dict__. I never check to see if an attribute |
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30 | # is defined in a base class. |
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31 | |||
32 | # Key: |
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33 | # +=========+=========================================+ |
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34 | # + Value | Meaning | |
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35 | # +=========+=========================================+ |
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36 | # | <blank> | No action: no method is added. | |
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37 | # +---------+-----------------------------------------+ |
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38 | # | add | Generated method is added. | |
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39 | # +---------+-----------------------------------------+ |
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40 | # | raise | TypeError is raised. | |
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41 | # +---------+-----------------------------------------+ |
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42 | # | None | Attribute is set to None. | |
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43 | # +=========+=========================================+ |
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44 | |||
45 | # __init__ |
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46 | # |
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47 | # +--- init= parameter |
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48 | # | |
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49 | # v | | | |
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50 | # | no | yes | <--- class has __init__ in __dict__? |
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51 | # +=======+=======+=======+ |
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52 | # | False | | | |
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53 | # +-------+-------+-------+ |
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54 | # | True | add | | <- the default |
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55 | # +=======+=======+=======+ |
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56 | |||
57 | # __repr__ |
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58 | # |
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59 | # +--- repr= parameter |
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60 | # | |
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61 | # v | | | |
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62 | # | no | yes | <--- class has __repr__ in __dict__? |
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63 | # +=======+=======+=======+ |
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64 | # | False | | | |
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65 | # +-------+-------+-------+ |
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66 | # | True | add | | <- the default |
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67 | # +=======+=======+=======+ |
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68 | |||
69 | |||
70 | # __setattr__ |
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71 | # __delattr__ |
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72 | # |
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73 | # +--- frozen= parameter |
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74 | # | |
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75 | # v | | | |
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76 | # | no | yes | <--- class has __setattr__ or __delattr__ in __dict__? |
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77 | # +=======+=======+=======+ |
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78 | # | False | | | <- the default |
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79 | # +-------+-------+-------+ |
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80 | # | True | add | raise | |
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81 | # +=======+=======+=======+ |
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82 | # Raise because not adding these methods would break the "frozen-ness" |
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83 | # of the class. |
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84 | |||
85 | # __eq__ |
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86 | # |
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87 | # +--- eq= parameter |
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88 | # | |
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89 | # v | | | |
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90 | # | no | yes | <--- class has __eq__ in __dict__? |
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91 | # +=======+=======+=======+ |
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92 | # | False | | | |
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93 | # +-------+-------+-------+ |
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94 | # | True | add | | <- the default |
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95 | # +=======+=======+=======+ |
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96 | |||
97 | # __lt__ |
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98 | # __le__ |
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99 | # __gt__ |
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100 | # __ge__ |
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101 | # |
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102 | # +--- order= parameter |
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103 | # | |
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104 | # v | | | |
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105 | # | no | yes | <--- class has any comparison method in __dict__? |
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106 | # +=======+=======+=======+ |
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107 | # | False | | | <- the default |
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108 | # +-------+-------+-------+ |
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109 | # | True | add | raise | |
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110 | # +=======+=======+=======+ |
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111 | # Raise because to allow this case would interfere with using |
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112 | # functools.total_ordering. |
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113 | |||
114 | # __hash__ |
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115 | |||
116 | # +------------------- unsafe_hash= parameter |
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117 | # | +----------- eq= parameter |
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118 | # | | +--- frozen= parameter |
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119 | # | | | |
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120 | # v v v | | | |
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121 | # | no | yes | <--- class has explicitly defined __hash__ |
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122 | # +=======+=======+=======+========+========+ |
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123 | # | False | False | False | | | No __eq__, use the base class __hash__ |
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124 | # +-------+-------+-------+--------+--------+ |
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125 | # | False | False | True | | | No __eq__, use the base class __hash__ |
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126 | # +-------+-------+-------+--------+--------+ |
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127 | # | False | True | False | None | | <-- the default, not hashable |
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128 | # +-------+-------+-------+--------+--------+ |
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129 | # | False | True | True | add | | Frozen, so hashable, allows override |
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130 | # +-------+-------+-------+--------+--------+ |
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131 | # | True | False | False | add | raise | Has no __eq__, but hashable |
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132 | # +-------+-------+-------+--------+--------+ |
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133 | # | True | False | True | add | raise | Has no __eq__, but hashable |
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134 | # +-------+-------+-------+--------+--------+ |
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135 | # | True | True | False | add | raise | Not frozen, but hashable |
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136 | # +-------+-------+-------+--------+--------+ |
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137 | # | True | True | True | add | raise | Frozen, so hashable |
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138 | # +=======+=======+=======+========+========+ |
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139 | # For boxes that are blank, __hash__ is untouched and therefore |
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140 | # inherited from the base class. If the base is object, then |
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141 | # id-based hashing is used. |
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142 | # |
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143 | # Note that a class may already have __hash__=None if it specified an |
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144 | # __eq__ method in the class body (not one that was created by |
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145 | # @dataclass). |
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146 | # |
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147 | # See _hash_action (below) for a coded version of this table. |
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148 | |||
149 | |||
150 | # Raised when an attempt is made to modify a frozen class. |
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151 | class FrozenInstanceError(AttributeError): pass |
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152 | |||
153 | # A sentinel object for default values to signal that a default |
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154 | # factory will be used. This is given a nice repr() which will appear |
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155 | # in the function signature of dataclasses' constructors. |
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156 | class _HAS_DEFAULT_FACTORY_CLASS: |
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157 | def __repr__(self): |
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158 | return '<factory>' |
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159 | _HAS_DEFAULT_FACTORY = _HAS_DEFAULT_FACTORY_CLASS() |
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160 | |||
161 | # A sentinel object to detect if a parameter is supplied or not. Use |
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162 | # a class to give it a better repr. |
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163 | class _MISSING_TYPE: |
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164 | pass |
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165 | MISSING = _MISSING_TYPE() |
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166 | |||
167 | # Since most per-field metadata will be unused, create an empty |
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168 | # read-only proxy that can be shared among all fields. |
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169 | _EMPTY_METADATA = types.MappingProxyType({}) |
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170 | |||
171 | # Markers for the various kinds of fields and pseudo-fields. |
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172 | class _FIELD_BASE: |
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173 | def __init__(self, name): |
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174 | self.name = name |
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175 | def __repr__(self): |
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176 | return self.name |
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177 | _FIELD = _FIELD_BASE('_FIELD') |
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178 | _FIELD_CLASSVAR = _FIELD_BASE('_FIELD_CLASSVAR') |
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179 | _FIELD_INITVAR = _FIELD_BASE('_FIELD_INITVAR') |
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180 | |||
181 | # The name of an attribute on the class where we store the Field |
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182 | # objects. Also used to check if a class is a Data Class. |
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183 | _FIELDS = '__dataclass_fields__' |
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184 | |||
185 | # The name of an attribute on the class that stores the parameters to |
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186 | # @dataclass. |
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187 | _PARAMS = '__dataclass_params__' |
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188 | |||
189 | # The name of the function, that if it exists, is called at the end of |
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190 | # __init__. |
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191 | _POST_INIT_NAME = '__post_init__' |
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192 | |||
193 | # String regex that string annotations for ClassVar or InitVar must match. |
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194 | # Allows "identifier.identifier[" or "identifier[". |
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195 | # https://bugs.python.org/issue33453 for details. |
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196 | _MODULE_IDENTIFIER_RE = re.compile(r'^(?:\s*(\w+)\s*\.)?\s*(\w+)') |
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197 | |||
198 | class _InitVarMeta(type): |
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199 | def __getitem__(self, params): |
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200 | return self |
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201 | |||
202 | class InitVar(metaclass=_InitVarMeta): |
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203 | pass |
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204 | |||
205 | |||
206 | # Instances of Field are only ever created from within this module, |
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207 | # and only from the field() function, although Field instances are |
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208 | # exposed externally as (conceptually) read-only objects. |
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209 | # |
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210 | # name and type are filled in after the fact, not in __init__. |
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211 | # They're not known at the time this class is instantiated, but it's |
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212 | # convenient if they're available later. |
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213 | # |
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214 | # When cls._FIELDS is filled in with a list of Field objects, the name |
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215 | # and type fields will have been populated. |
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216 | class Field: |
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217 | __slots__ = ('name', |
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218 | 'type', |
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219 | 'default', |
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220 | 'default_factory', |
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221 | 'repr', |
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222 | 'hash', |
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223 | 'init', |
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224 | 'compare', |
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225 | 'metadata', |
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226 | '_field_type', # Private: not to be used by user code. |
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227 | ) |
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228 | |||
229 | def __init__(self, default, default_factory, init, repr, hash, compare, |
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230 | metadata): |
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231 | self.name = None |
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232 | self.type = None |
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233 | self.default = default |
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234 | self.default_factory = default_factory |
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235 | self.init = init |
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236 | self.repr = repr |
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237 | self.hash = hash |
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238 | self.compare = compare |
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239 | self.metadata = (_EMPTY_METADATA |
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240 | if metadata is None or len(metadata) == 0 else |
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241 | types.MappingProxyType(metadata)) |
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242 | self._field_type = None |
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243 | |||
244 | def __repr__(self): |
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245 | return ('Field(' |
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246 | f'name={self.name!r},' |
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247 | f'type={self.type!r},' |
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248 | f'default={self.default!r},' |
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249 | f'default_factory={self.default_factory!r},' |
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250 | f'init={self.init!r},' |
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251 | f'repr={self.repr!r},' |
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252 | f'hash={self.hash!r},' |
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253 | f'compare={self.compare!r},' |
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254 | f'metadata={self.metadata!r},' |
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255 | f'_field_type={self._field_type}' |
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256 | ')') |
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257 | |||
258 | # This is used to support the PEP 487 __set_name__ protocol in the |
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259 | # case where we're using a field that contains a descriptor as a |
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260 | # default value. For details on __set_name__, see |
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261 | # https://www.python.org/dev/peps/pep-0487/#implementation-details. |
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262 | # |
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263 | # Note that in _process_class, this Field object is overwritten |
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264 | # with the default value, so the end result is a descriptor that |
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265 | # had __set_name__ called on it at the right time. |
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266 | def __set_name__(self, owner, name): |
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267 | func = getattr(type(self.default), '__set_name__', None) |
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268 | if func: |
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269 | # There is a __set_name__ method on the descriptor, call |
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270 | # it. |
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271 | func(self.default, owner, name) |
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272 | |||
273 | |||
274 | class _DataclassParams: |
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275 | __slots__ = ('init', |
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276 | 'repr', |
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277 | 'eq', |
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278 | 'order', |
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279 | 'unsafe_hash', |
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280 | 'frozen', |
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281 | ) |
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282 | |||
283 | def __init__(self, init, repr, eq, order, unsafe_hash, frozen): |
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284 | self.init = init |
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285 | self.repr = repr |
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286 | self.eq = eq |
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287 | self.order = order |
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288 | self.unsafe_hash = unsafe_hash |
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289 | self.frozen = frozen |
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290 | |||
291 | def __repr__(self): |
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292 | return ('_DataclassParams(' |
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293 | f'init={self.init!r},' |
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294 | f'repr={self.repr!r},' |
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295 | f'eq={self.eq!r},' |
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296 | f'order={self.order!r},' |
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297 | f'unsafe_hash={self.unsafe_hash!r},' |
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298 | f'frozen={self.frozen!r}' |
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299 | ')') |
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300 | |||
301 | |||
302 | # This function is used instead of exposing Field creation directly, |
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303 | # so that a type checker can be told (via overloads) that this is a |
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304 | # function whose type depends on its parameters. |
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305 | def field(*, default=MISSING, default_factory=MISSING, init=True, repr=True, |
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306 | hash=None, compare=True, metadata=None): |
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307 | """Return an object to identify dataclass fields. |
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308 | |||
309 | default is the default value of the field. default_factory is a |
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310 | 0-argument function called to initialize a field's value. If init |
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311 | is True, the field will be a parameter to the class's __init__() |
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312 | function. If repr is True, the field will be included in the |
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313 | object's repr(). If hash is True, the field will be included in |
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314 | the object's hash(). If compare is True, the field will be used |
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315 | in comparison functions. metadata, if specified, must be a |
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316 | mapping which is stored but not otherwise examined by dataclass. |
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317 | |||
318 | It is an error to specify both default and default_factory. |
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319 | """ |
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320 | |||
321 | if default is not MISSING and default_factory is not MISSING: |
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322 | raise ValueError('cannot specify both default and default_factory') |
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323 | return Field(default, default_factory, init, repr, hash, compare, |
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324 | metadata) |
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325 | |||
326 | |||
327 | def _tuple_str(obj_name, fields): |
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328 | # Return a string representing each field of obj_name as a tuple |
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329 | # member. So, if fields is ['x', 'y'] and obj_name is "self", |
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330 | # return "(self.x,self.y)". |
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331 | |||
332 | # Special case for the 0-tuple. |
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333 | if not fields: |
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334 | return '()' |
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335 | # Note the trailing comma, needed if this turns out to be a 1-tuple. |
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336 | return f'({",".join([f"{obj_name}.{f.name}" for f in fields])},)' |
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337 | |||
338 | |||
339 | def _create_fn(name, args, body, *, globals=None, locals=None, |
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340 | return_type=MISSING): |
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341 | # Note that we mutate locals when exec() is called. Caller |
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342 | # beware! The only callers are internal to this module, so no |
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343 | # worries about external callers. |
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344 | if locals is None: |
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345 | locals = {} |
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346 | return_annotation = '' |
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347 | if return_type is not MISSING: |
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348 | locals['_return_type'] = return_type |
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349 | return_annotation = '->_return_type' |
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350 | args = ','.join(args) |
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351 | body = '\n'.join(f' {b}' for b in body) |
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352 | |||
353 | # Compute the text of the entire function. |
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354 | txt = f'def {name}({args}){return_annotation}:\n{body}' |
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355 | |||
356 | exec(txt, globals, locals) |
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357 | return locals[name] |
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358 | |||
359 | |||
360 | def _field_assign(frozen, name, value, self_name): |
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361 | # If we're a frozen class, then assign to our fields in __init__ |
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362 | # via object.__setattr__. Otherwise, just use a simple |
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363 | # assignment. |
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364 | # |
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365 | # self_name is what "self" is called in this function: don't |
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366 | # hard-code "self", since that might be a field name. |
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367 | if frozen: |
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368 | return f'object.__setattr__({self_name},{name!r},{value})' |
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369 | return f'{self_name}.{name}={value}' |
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370 | |||
371 | |||
372 | def _field_init(f, frozen, globals, self_name): |
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373 | # Return the text of the line in the body of __init__ that will |
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374 | # initialize this field. |
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375 | |||
376 | default_name = f'_dflt_{f.name}' |
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377 | if f.default_factory is not MISSING: |
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378 | if f.init: |
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379 | # This field has a default factory. If a parameter is |
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380 | # given, use it. If not, call the factory. |
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381 | globals[default_name] = f.default_factory |
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382 | value = (f'{default_name}() ' |
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383 | f'if {f.name} is _HAS_DEFAULT_FACTORY ' |
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384 | f'else {f.name}') |
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385 | else: |
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386 | # This is a field that's not in the __init__ params, but |
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387 | # has a default factory function. It needs to be |
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388 | # initialized here by calling the factory function, |
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389 | # because there's no other way to initialize it. |
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390 | |||
391 | # For a field initialized with a default=defaultvalue, the |
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392 | # class dict just has the default value |
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393 | # (cls.fieldname=defaultvalue). But that won't work for a |
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394 | # default factory, the factory must be called in __init__ |
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395 | # and we must assign that to self.fieldname. We can't |
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396 | # fall back to the class dict's value, both because it's |
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397 | # not set, and because it might be different per-class |
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398 | # (which, after all, is why we have a factory function!). |
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399 | |||
400 | globals[default_name] = f.default_factory |
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401 | value = f'{default_name}()' |
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402 | else: |
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403 | # No default factory. |
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404 | if f.init: |
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405 | if f.default is MISSING: |
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406 | # There's no default, just do an assignment. |
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407 | value = f.name |
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408 | elif f.default is not MISSING: |
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409 | globals[default_name] = f.default |
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410 | value = f.name |
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411 | else: |
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412 | # This field does not need initialization. Signify that |
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413 | # to the caller by returning None. |
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414 | return None |
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415 | |||
416 | # Only test this now, so that we can create variables for the |
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417 | # default. However, return None to signify that we're not going |
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418 | # to actually do the assignment statement for InitVars. |
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419 | if f._field_type is _FIELD_INITVAR: |
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420 | return None |
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421 | |||
422 | # Now, actually generate the field assignment. |
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423 | return _field_assign(frozen, f.name, value, self_name) |
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424 | |||
425 | |||
426 | def _init_param(f): |
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427 | # Return the __init__ parameter string for this field. For |
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428 | # example, the equivalent of 'x:int=3' (except instead of 'int', |
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429 | # reference a variable set to int, and instead of '3', reference a |
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430 | # variable set to 3). |
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431 | if f.default is MISSING and f.default_factory is MISSING: |
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432 | # There's no default, and no default_factory, just output the |
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433 | # variable name and type. |
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434 | default = '' |
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435 | elif f.default is not MISSING: |
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436 | # There's a default, this will be the name that's used to look |
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437 | # it up. |
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438 | default = f'=_dflt_{f.name}' |
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439 | elif f.default_factory is not MISSING: |
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440 | # There's a factory function. Set a marker. |
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441 | default = '=_HAS_DEFAULT_FACTORY' |
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442 | return f'{f.name}:_type_{f.name}{default}' |
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443 | |||
444 | |||
445 | def _init_fn(fields, frozen, has_post_init, self_name): |
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446 | # fields contains both real fields and InitVar pseudo-fields. |
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447 | |||
448 | # Make sure we don't have fields without defaults following fields |
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449 | # with defaults. This actually would be caught when exec-ing the |
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450 | # function source code, but catching it here gives a better error |
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451 | # message, and future-proofs us in case we build up the function |
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452 | # using ast. |
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453 | seen_default = False |
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454 | for f in fields: |
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455 | # Only consider fields in the __init__ call. |
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456 | if f.init: |
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457 | if not (f.default is MISSING and f.default_factory is MISSING): |
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458 | seen_default = True |
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459 | elif seen_default: |
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460 | raise TypeError(f'non-default argument {f.name!r} ' |
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461 | 'follows default argument') |
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462 | |||
463 | globals = {'MISSING': MISSING, |
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464 | '_HAS_DEFAULT_FACTORY': _HAS_DEFAULT_FACTORY} |
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465 | |||
466 | body_lines = [] |
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467 | for f in fields: |
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468 | line = _field_init(f, frozen, globals, self_name) |
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469 | # line is None means that this field doesn't require |
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470 | # initialization (it's a pseudo-field). Just skip it. |
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471 | if line: |
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472 | body_lines.append(line) |
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473 | |||
474 | # Does this class have a post-init function? |
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475 | if has_post_init: |
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476 | params_str = ','.join(f.name for f in fields |
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477 | if f._field_type is _FIELD_INITVAR) |
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478 | body_lines.append(f'{self_name}.{_POST_INIT_NAME}({params_str})') |
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479 | |||
480 | # If no body lines, use 'pass'. |
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481 | if not body_lines: |
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482 | body_lines = ['pass'] |
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483 | |||
484 | locals = {f'_type_{f.name}': f.type for f in fields} |
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485 | return _create_fn('__init__', |
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486 | [self_name] + [_init_param(f) for f in fields if f.init], |
||
487 | body_lines, |
||
488 | locals=locals, |
||
489 | globals=globals, |
||
490 | return_type=None) |
||
491 | |||
492 | |||
493 | def _repr_fn(fields): |
||
494 | return _create_fn('__repr__', |
||
495 | ('self',), |
||
496 | ['return self.__class__.__qualname__ + f"(' + |
||
497 | ', '.join([f"{f.name}={{self.{f.name}!r}}" |
||
498 | for f in fields]) + |
||
499 | ')"']) |
||
500 | |||
501 | |||
502 | def _frozen_get_del_attr(cls, fields): |
||
503 | # XXX: globals is modified on the first call to _create_fn, then |
||
504 | # the modified version is used in the second call. Is this okay? |
||
505 | globals = {'cls': cls, |
||
506 | 'FrozenInstanceError': FrozenInstanceError} |
||
507 | if fields: |
||
508 | fields_str = '(' + ','.join(repr(f.name) for f in fields) + ',)' |
||
509 | else: |
||
510 | # Special case for the zero-length tuple. |
||
511 | fields_str = '()' |
||
512 | return (_create_fn('__setattr__', |
||
513 | ('self', 'name', 'value'), |
||
514 | (f'if type(self) is cls or name in {fields_str}:', |
||
515 | ' raise FrozenInstanceError(f"cannot assign to field {name!r}")', |
||
516 | f'super(cls, self).__setattr__(name, value)'), |
||
517 | globals=globals), |
||
518 | _create_fn('__delattr__', |
||
519 | ('self', 'name'), |
||
520 | (f'if type(self) is cls or name in {fields_str}:', |
||
521 | ' raise FrozenInstanceError(f"cannot delete field {name!r}")', |
||
522 | f'super(cls, self).__delattr__(name)'), |
||
523 | globals=globals), |
||
524 | ) |
||
525 | |||
526 | |||
527 | def _cmp_fn(name, op, self_tuple, other_tuple): |
||
528 | # Create a comparison function. If the fields in the object are |
||
529 | # named 'x' and 'y', then self_tuple is the string |
||
530 | # '(self.x,self.y)' and other_tuple is the string |
||
531 | # '(other.x,other.y)'. |
||
532 | |||
533 | return _create_fn(name, |
||
534 | ('self', 'other'), |
||
535 | [ 'if other.__class__ is self.__class__:', |
||
536 | f' return {self_tuple}{op}{other_tuple}', |
||
537 | 'return NotImplemented']) |
||
538 | |||
539 | |||
540 | def _hash_fn(fields): |
||
541 | self_tuple = _tuple_str('self', fields) |
||
542 | return _create_fn('__hash__', |
||
543 | ('self',), |
||
544 | [f'return hash({self_tuple})']) |
||
545 | |||
546 | |||
547 | def _is_classvar(a_type, typing): |
||
548 | # This test uses a typing internal class, but it's the best way to |
||
549 | # test if this is a ClassVar. |
||
550 | return type(a_type) is typing._ClassVar |
||
551 | |||
552 | |||
553 | def _is_initvar(a_type, dataclasses): |
||
554 | # The module we're checking against is the module we're |
||
555 | # currently in (dataclasses.py). |
||
556 | return a_type is dataclasses.InitVar |
||
557 | |||
558 | |||
559 | def _is_type(annotation, cls, a_module, a_type, is_type_predicate): |
||
560 | # Given a type annotation string, does it refer to a_type in |
||
561 | # a_module? For example, when checking that annotation denotes a |
||
562 | # ClassVar, then a_module is typing, and a_type is |
||
563 | # typing.ClassVar. |
||
564 | |||
565 | # It's possible to look up a_module given a_type, but it involves |
||
566 | # looking in sys.modules (again!), and seems like a waste since |
||
567 | # the caller already knows a_module. |
||
568 | |||
569 | # - annotation is a string type annotation |
||
570 | # - cls is the class that this annotation was found in |
||
571 | # - a_module is the module we want to match |
||
572 | # - a_type is the type in that module we want to match |
||
573 | # - is_type_predicate is a function called with (obj, a_module) |
||
574 | # that determines if obj is of the desired type. |
||
575 | |||
576 | # Since this test does not do a local namespace lookup (and |
||
577 | # instead only a module (global) lookup), there are some things it |
||
578 | # gets wrong. |
||
579 | |||
580 | # With string annotations, cv0 will be detected as a ClassVar: |
||
581 | # CV = ClassVar |
||
582 | # @dataclass |
||
583 | # class C0: |
||
584 | # cv0: CV |
||
585 | |||
586 | # But in this example cv1 will not be detected as a ClassVar: |
||
587 | # @dataclass |
||
588 | # class C1: |
||
589 | # CV = ClassVar |
||
590 | # cv1: CV |
||
591 | |||
592 | # In C1, the code in this function (_is_type) will look up "CV" in |
||
593 | # the module and not find it, so it will not consider cv1 as a |
||
594 | # ClassVar. This is a fairly obscure corner case, and the best |
||
595 | # way to fix it would be to eval() the string "CV" with the |
||
596 | # correct global and local namespaces. However that would involve |
||
597 | # a eval() penalty for every single field of every dataclass |
||
598 | # that's defined. It was judged not worth it. |
||
599 | |||
600 | match = _MODULE_IDENTIFIER_RE.match(annotation) |
||
601 | if match: |
||
602 | ns = None |
||
603 | module_name = match.group(1) |
||
604 | if not module_name: |
||
605 | # No module name, assume the class's module did |
||
606 | # "from .dataclasses import InitVar". |
||
607 | ns = sys.modules.get(cls.__module__).__dict__ |
||
608 | else: |
||
609 | # Look up module_name in the class's module. |
||
610 | module = sys.modules.get(cls.__module__) |
||
611 | if module and module.__dict__.get(module_name) is a_module: |
||
612 | ns = sys.modules.get(a_type.__module__).__dict__ |
||
613 | if ns and is_type_predicate(ns.get(match.group(2)), a_module): |
||
614 | return True |
||
615 | return False |
||
616 | |||
617 | |||
618 | def _get_field(cls, a_name, a_type): |
||
619 | # Return a Field object for this field name and type. ClassVars |
||
620 | # and InitVars are also returned, but marked as such (see |
||
621 | # f._field_type). |
||
622 | |||
623 | # If the default value isn't derived from Field, then it's only a |
||
624 | # normal default value. Convert it to a Field(). |
||
625 | default = getattr(cls, a_name, MISSING) |
||
626 | if isinstance(default, Field): |
||
627 | f = default |
||
628 | else: |
||
629 | if isinstance(default, types.MemberDescriptorType): |
||
630 | # This is a field in __slots__, so it has no default value. |
||
631 | default = MISSING |
||
632 | f = field(default=default) |
||
633 | |||
634 | # Only at this point do we know the name and the type. Set them. |
||
635 | f.name = a_name |
||
636 | f.type = a_type |
||
637 | |||
638 | # Assume it's a normal field until proven otherwise. We're next |
||
639 | # going to decide if it's a ClassVar or InitVar, everything else |
||
640 | # is just a normal field. |
||
641 | f._field_type = _FIELD |
||
642 | |||
643 | # In addition to checking for actual types here, also check for |
||
644 | # string annotations. get_type_hints() won't always work for us |
||
645 | # (see https://github.com/python/typing/issues/508 for example), |
||
646 | # plus it's expensive and would require an eval for every string |
||
647 | # annotation. So, make a best effort to see if this is a ClassVar |
||
648 | # or InitVar using regex's and checking that the thing referenced |
||
649 | # is actually of the correct type. |
||
650 | |||
651 | # For the complete discussion, see https://bugs.python.org/issue33453 |
||
652 | |||
653 | # If typing has not been imported, then it's impossible for any |
||
654 | # annotation to be a ClassVar. So, only look for ClassVar if |
||
655 | # typing has been imported by any module (not necessarily cls's |
||
656 | # module). |
||
657 | typing = sys.modules.get('typing') |
||
658 | if typing: |
||
659 | if (_is_classvar(a_type, typing) |
||
660 | or (isinstance(f.type, str) |
||
661 | and _is_type(f.type, cls, typing, typing.ClassVar, |
||
662 | _is_classvar))): |
||
663 | f._field_type = _FIELD_CLASSVAR |
||
664 | |||
665 | # If the type is InitVar, or if it's a matching string annotation, |
||
666 | # then it's an InitVar. |
||
667 | if f._field_type is _FIELD: |
||
668 | # The module we're checking against is the module we're |
||
669 | # currently in (dataclasses.py). |
||
670 | dataclasses = sys.modules[__name__] |
||
671 | if (_is_initvar(a_type, dataclasses) |
||
672 | or (isinstance(f.type, str) |
||
673 | and _is_type(f.type, cls, dataclasses, dataclasses.InitVar, |
||
674 | _is_initvar))): |
||
675 | f._field_type = _FIELD_INITVAR |
||
676 | |||
677 | # Validations for individual fields. This is delayed until now, |
||
678 | # instead of in the Field() constructor, since only here do we |
||
679 | # know the field name, which allows for better error reporting. |
||
680 | |||
681 | # Special restrictions for ClassVar and InitVar. |
||
682 | if f._field_type in (_FIELD_CLASSVAR, _FIELD_INITVAR): |
||
683 | if f.default_factory is not MISSING: |
||
684 | raise TypeError(f'field {f.name} cannot have a ' |
||
685 | 'default factory') |
||
686 | # Should I check for other field settings? default_factory |
||
687 | # seems the most serious to check for. Maybe add others. For |
||
688 | # example, how about init=False (or really, |
||
689 | # init=<not-the-default-init-value>)? It makes no sense for |
||
690 | # ClassVar and InitVar to specify init=<anything>. |
||
691 | |||
692 | # For real fields, disallow mutable defaults for known types. |
||
693 | if f._field_type is _FIELD and isinstance(f.default, (list, dict, set)): |
||
694 | raise ValueError(f'mutable default {type(f.default)} for field ' |
||
695 | f'{f.name} is not allowed: use default_factory') |
||
696 | |||
697 | return f |
||
698 | |||
699 | |||
700 | def _set_new_attribute(cls, name, value): |
||
701 | # Never overwrites an existing attribute. Returns True if the |
||
702 | # attribute already exists. |
||
703 | if name in cls.__dict__: |
||
704 | return True |
||
705 | setattr(cls, name, value) |
||
706 | return False |
||
707 | |||
708 | |||
709 | # Decide if/how we're going to create a hash function. Key is |
||
710 | # (unsafe_hash, eq, frozen, does-hash-exist). Value is the action to |
||
711 | # take. The common case is to do nothing, so instead of providing a |
||
712 | # function that is a no-op, use None to signify that. |
||
713 | |||
714 | def _hash_set_none(cls, fields): |
||
715 | return None |
||
716 | |||
717 | def _hash_add(cls, fields): |
||
718 | flds = [f for f in fields if (f.compare if f.hash is None else f.hash)] |
||
719 | return _hash_fn(flds) |
||
720 | |||
721 | def _hash_exception(cls, fields): |
||
722 | # Raise an exception. |
||
723 | raise TypeError(f'Cannot overwrite attribute __hash__ ' |
||
724 | f'in class {cls.__name__}') |
||
725 | |||
726 | # |
||
727 | # +-------------------------------------- unsafe_hash? |
||
728 | # | +------------------------------- eq? |
||
729 | # | | +------------------------ frozen? |
||
730 | # | | | +---------------- has-explicit-hash? |
||
731 | # | | | | |
||
732 | # | | | | +------- action |
||
733 | # | | | | | |
||
734 | # v v v v v |
||
735 | _hash_action = {(False, False, False, False): None, |
||
736 | (False, False, False, True ): None, |
||
737 | (False, False, True, False): None, |
||
738 | (False, False, True, True ): None, |
||
739 | (False, True, False, False): _hash_set_none, |
||
740 | (False, True, False, True ): None, |
||
741 | (False, True, True, False): _hash_add, |
||
742 | (False, True, True, True ): None, |
||
743 | (True, False, False, False): _hash_add, |
||
744 | (True, False, False, True ): _hash_exception, |
||
745 | (True, False, True, False): _hash_add, |
||
746 | (True, False, True, True ): _hash_exception, |
||
747 | (True, True, False, False): _hash_add, |
||
748 | (True, True, False, True ): _hash_exception, |
||
749 | (True, True, True, False): _hash_add, |
||
750 | (True, True, True, True ): _hash_exception, |
||
751 | } |
||
752 | # See https://bugs.python.org/issue32929#msg312829 for an if-statement |
||
753 | # version of this table. |
||
754 | |||
755 | |||
756 | def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen): |
||
757 | # Now that dicts retain insertion order, there's no reason to use |
||
758 | # an ordered dict. I am leveraging that ordering here, because |
||
759 | # derived class fields overwrite base class fields, but the order |
||
760 | # is defined by the base class, which is found first. |
||
761 | fields = {} |
||
762 | |||
763 | setattr(cls, _PARAMS, _DataclassParams(init, repr, eq, order, |
||
764 | unsafe_hash, frozen)) |
||
765 | |||
766 | # Find our base classes in reverse MRO order, and exclude |
||
767 | # ourselves. In reversed order so that more derived classes |
||
768 | # override earlier field definitions in base classes. As long as |
||
769 | # we're iterating over them, see if any are frozen. |
||
770 | any_frozen_base = False |
||
771 | has_dataclass_bases = False |
||
772 | for b in cls.__mro__[-1:0:-1]: |
||
773 | # Only process classes that have been processed by our |
||
774 | # decorator. That is, they have a _FIELDS attribute. |
||
775 | base_fields = getattr(b, _FIELDS, None) |
||
776 | if base_fields: |
||
777 | has_dataclass_bases = True |
||
778 | for f in base_fields.values(): |
||
779 | fields[f.name] = f |
||
780 | if getattr(b, _PARAMS).frozen: |
||
781 | any_frozen_base = True |
||
782 | |||
783 | # Annotations that are defined in this class (not in base |
||
784 | # classes). If __annotations__ isn't present, then this class |
||
785 | # adds no new annotations. We use this to compute fields that are |
||
786 | # added by this class. |
||
787 | # |
||
788 | # Fields are found from cls_annotations, which is guaranteed to be |
||
789 | # ordered. Default values are from class attributes, if a field |
||
790 | # has a default. If the default value is a Field(), then it |
||
791 | # contains additional info beyond (and possibly including) the |
||
792 | # actual default value. Pseudo-fields ClassVars and InitVars are |
||
793 | # included, despite the fact that they're not real fields. That's |
||
794 | # dealt with later. |
||
795 | cls_annotations = cls.__dict__.get('__annotations__', {}) |
||
796 | |||
797 | # Now find fields in our class. While doing so, validate some |
||
798 | # things, and set the default values (as class attributes) where |
||
799 | # we can. |
||
800 | cls_fields = [_get_field(cls, name, type) |
||
801 | for name, type in cls_annotations.items()] |
||
802 | for f in cls_fields: |
||
803 | fields[f.name] = f |
||
804 | |||
805 | # If the class attribute (which is the default value for this |
||
806 | # field) exists and is of type 'Field', replace it with the |
||
807 | # real default. This is so that normal class introspection |
||
808 | # sees a real default value, not a Field. |
||
809 | if isinstance(getattr(cls, f.name, None), Field): |
||
810 | if f.default is MISSING: |
||
811 | # If there's no default, delete the class attribute. |
||
812 | # This happens if we specify field(repr=False), for |
||
813 | # example (that is, we specified a field object, but |
||
814 | # no default value). Also if we're using a default |
||
815 | # factory. The class attribute should not be set at |
||
816 | # all in the post-processed class. |
||
817 | delattr(cls, f.name) |
||
818 | else: |
||
819 | setattr(cls, f.name, f.default) |
||
820 | |||
821 | # Do we have any Field members that don't also have annotations? |
||
822 | for name, value in cls.__dict__.items(): |
||
823 | if isinstance(value, Field) and not name in cls_annotations: |
||
824 | raise TypeError(f'{name!r} is a field but has no type annotation') |
||
825 | |||
826 | # Check rules that apply if we are derived from any dataclasses. |
||
827 | if has_dataclass_bases: |
||
828 | # Raise an exception if any of our bases are frozen, but we're not. |
||
829 | if any_frozen_base and not frozen: |
||
830 | raise TypeError('cannot inherit non-frozen dataclass from a ' |
||
831 | 'frozen one') |
||
832 | |||
833 | # Raise an exception if we're frozen, but none of our bases are. |
||
834 | if not any_frozen_base and frozen: |
||
835 | raise TypeError('cannot inherit frozen dataclass from a ' |
||
836 | 'non-frozen one') |
||
837 | |||
838 | # Remember all of the fields on our class (including bases). This |
||
839 | # also marks this class as being a dataclass. |
||
840 | setattr(cls, _FIELDS, fields) |
||
841 | |||
842 | # Was this class defined with an explicit __hash__? Note that if |
||
843 | # __eq__ is defined in this class, then python will automatically |
||
844 | # set __hash__ to None. This is a heuristic, as it's possible |
||
845 | # that such a __hash__ == None was not auto-generated, but it |
||
846 | # close enough. |
||
847 | class_hash = cls.__dict__.get('__hash__', MISSING) |
||
848 | has_explicit_hash = not (class_hash is MISSING or |
||
849 | (class_hash is None and '__eq__' in cls.__dict__)) |
||
850 | |||
851 | # If we're generating ordering methods, we must be generating the |
||
852 | # eq methods. |
||
853 | if order and not eq: |
||
854 | raise ValueError('eq must be true if order is true') |
||
855 | |||
856 | if init: |
||
857 | # Does this class have a post-init function? |
||
858 | has_post_init = hasattr(cls, _POST_INIT_NAME) |
||
859 | |||
860 | # Include InitVars and regular fields (so, not ClassVars). |
||
861 | flds = [f for f in fields.values() |
||
862 | if f._field_type in (_FIELD, _FIELD_INITVAR)] |
||
863 | _set_new_attribute(cls, '__init__', |
||
864 | _init_fn(flds, |
||
865 | frozen, |
||
866 | has_post_init, |
||
867 | # The name to use for the "self" |
||
868 | # param in __init__. Use "self" |
||
869 | # if possible. |
||
870 | '__dataclass_self__' if 'self' in fields |
||
871 | else 'self', |
||
872 | )) |
||
873 | |||
874 | # Get the fields as a list, and include only real fields. This is |
||
875 | # used in all of the following methods. |
||
876 | field_list = [f for f in fields.values() if f._field_type is _FIELD] |
||
877 | |||
878 | if repr: |
||
879 | flds = [f for f in field_list if f.repr] |
||
880 | _set_new_attribute(cls, '__repr__', _repr_fn(flds)) |
||
881 | |||
882 | if eq: |
||
883 | # Create _eq__ method. There's no need for a __ne__ method, |
||
884 | # since python will call __eq__ and negate it. |
||
885 | flds = [f for f in field_list if f.compare] |
||
886 | self_tuple = _tuple_str('self', flds) |
||
887 | other_tuple = _tuple_str('other', flds) |
||
888 | _set_new_attribute(cls, '__eq__', |
||
889 | _cmp_fn('__eq__', '==', |
||
890 | self_tuple, other_tuple)) |
||
891 | |||
892 | if order: |
||
893 | # Create and set the ordering methods. |
||
894 | flds = [f for f in field_list if f.compare] |
||
895 | self_tuple = _tuple_str('self', flds) |
||
896 | other_tuple = _tuple_str('other', flds) |
||
897 | for name, op in [('__lt__', '<'), |
||
898 | ('__le__', '<='), |
||
899 | ('__gt__', '>'), |
||
900 | ('__ge__', '>='), |
||
901 | ]: |
||
902 | if _set_new_attribute(cls, name, |
||
903 | _cmp_fn(name, op, self_tuple, other_tuple)): |
||
904 | raise TypeError(f'Cannot overwrite attribute {name} ' |
||
905 | f'in class {cls.__name__}. Consider using ' |
||
906 | 'functools.total_ordering') |
||
907 | |||
908 | if frozen: |
||
909 | for fn in _frozen_get_del_attr(cls, field_list): |
||
910 | if _set_new_attribute(cls, fn.__name__, fn): |
||
911 | raise TypeError(f'Cannot overwrite attribute {fn.__name__} ' |
||
912 | f'in class {cls.__name__}') |
||
913 | |||
914 | # Decide if/how we're going to create a hash function. |
||
915 | hash_action = _hash_action[bool(unsafe_hash), |
||
916 | bool(eq), |
||
917 | bool(frozen), |
||
918 | has_explicit_hash] |
||
919 | if hash_action: |
||
920 | # No need to call _set_new_attribute here, since by the time |
||
921 | # we're here the overwriting is unconditional. |
||
922 | cls.__hash__ = hash_action(cls, field_list) |
||
923 | |||
924 | if not getattr(cls, '__doc__'): |
||
925 | # Create a class doc-string. |
||
926 | cls.__doc__ = (cls.__name__ + |
||
927 | str(inspect.signature(cls)).replace(' -> None', '')) |
||
928 | |||
929 | return cls |
||
930 | |||
931 | |||
932 | # _cls should never be specified by keyword, so start it with an |
||
933 | # underscore. The presence of _cls is used to detect if this |
||
934 | # decorator is being called with parameters or not. |
||
935 | def dataclass(_cls=None, *, init=True, repr=True, eq=True, order=False, |
||
936 | unsafe_hash=False, frozen=False): |
||
937 | """Returns the same class as was passed in, with dunder methods |
||
938 | added based on the fields defined in the class. |
||
939 | |||
940 | Examines PEP 526 __annotations__ to determine fields. |
||
941 | |||
942 | If init is true, an __init__() method is added to the class. If |
||
943 | repr is true, a __repr__() method is added. If order is true, rich |
||
944 | comparison dunder methods are added. If unsafe_hash is true, a |
||
945 | __hash__() method function is added. If frozen is true, fields may |
||
946 | not be assigned to after instance creation. |
||
947 | """ |
||
948 | |||
949 | def wrap(cls): |
||
950 | return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen) |
||
951 | |||
952 | # See if we're being called as @dataclass or @dataclass(). |
||
953 | if _cls is None: |
||
954 | # We're called with parens. |
||
955 | return wrap |
||
956 | |||
957 | # We're called as @dataclass without parens. |
||
958 | return wrap(_cls) |
||
959 | |||
960 | |||
961 | def fields(class_or_instance): |
||
962 | """Return a tuple describing the fields of this dataclass. |
||
963 | |||
964 | Accepts a dataclass or an instance of one. Tuple elements are of |
||
965 | type Field. |
||
966 | """ |
||
967 | |||
968 | # Might it be worth caching this, per class? |
||
969 | try: |
||
970 | fields = getattr(class_or_instance, _FIELDS) |
||
971 | except AttributeError: |
||
972 | raise TypeError('must be called with a dataclass type or instance') |
||
973 | |||
974 | # Exclude pseudo-fields. Note that fields is sorted by insertion |
||
975 | # order, so the order of the tuple is as the fields were defined. |
||
976 | return tuple(f for f in fields.values() if f._field_type is _FIELD) |
||
977 | |||
978 | |||
979 | def _is_dataclass_instance(obj): |
||
980 | """Returns True if obj is an instance of a dataclass.""" |
||
981 | return not isinstance(obj, type) and hasattr(obj, _FIELDS) |
||
982 | |||
983 | |||
984 | def is_dataclass(obj): |
||
985 | """Returns True if obj is a dataclass or an instance of a |
||
986 | dataclass.""" |
||
987 | return hasattr(obj, _FIELDS) |
||
988 | |||
989 | |||
990 | def asdict(obj, *, dict_factory=dict): |
||
991 | """Return the fields of a dataclass instance as a new dictionary mapping |
||
992 | field names to field values. |
||
993 | |||
994 | Example usage: |
||
995 | |||
996 | @dataclass |
||
997 | class C: |
||
998 | x: int |
||
999 | y: int |
||
1000 | |||
1001 | c = C(1, 2) |
||
1002 | assert asdict(c) == {'x': 1, 'y': 2} |
||
1003 | |||
1004 | If given, 'dict_factory' will be used instead of built-in dict. |
||
1005 | The function applies recursively to field values that are |
||
1006 | dataclass instances. This will also look into built-in containers: |
||
1007 | tuples, lists, and dicts. |
||
1008 | """ |
||
1009 | if not _is_dataclass_instance(obj): |
||
1010 | raise TypeError("asdict() should be called on dataclass instances") |
||
1011 | return _asdict_inner(obj, dict_factory) |
||
1012 | |||
1013 | |||
1014 | View Code Duplication | def _asdict_inner(obj, dict_factory): |
|
1015 | if _is_dataclass_instance(obj): |
||
1016 | result = [] |
||
1017 | for f in fields(obj): |
||
1018 | value = _asdict_inner(getattr(obj, f.name), dict_factory) |
||
1019 | result.append((f.name, value)) |
||
1020 | return dict_factory(result) |
||
1021 | elif isinstance(obj, (list, tuple)): |
||
1022 | return type(obj)(_asdict_inner(v, dict_factory) for v in obj) |
||
1023 | elif isinstance(obj, dict): |
||
1024 | return type(obj)((_asdict_inner(k, dict_factory), _asdict_inner(v, dict_factory)) |
||
1025 | for k, v in obj.items()) |
||
1026 | else: |
||
1027 | return copy.deepcopy(obj) |
||
1028 | |||
1029 | |||
1030 | def astuple(obj, *, tuple_factory=tuple): |
||
1031 | """Return the fields of a dataclass instance as a new tuple of field values. |
||
1032 | |||
1033 | Example usage:: |
||
1034 | |||
1035 | @dataclass |
||
1036 | class C: |
||
1037 | x: int |
||
1038 | y: int |
||
1039 | |||
1040 | c = C(1, 2) |
||
1041 | assert astuple(c) == (1, 2) |
||
1042 | |||
1043 | If given, 'tuple_factory' will be used instead of built-in tuple. |
||
1044 | The function applies recursively to field values that are |
||
1045 | dataclass instances. This will also look into built-in containers: |
||
1046 | tuples, lists, and dicts. |
||
1047 | """ |
||
1048 | |||
1049 | if not _is_dataclass_instance(obj): |
||
1050 | raise TypeError("astuple() should be called on dataclass instances") |
||
1051 | return _astuple_inner(obj, tuple_factory) |
||
1052 | |||
1053 | |||
1054 | View Code Duplication | def _astuple_inner(obj, tuple_factory): |
|
1055 | if _is_dataclass_instance(obj): |
||
1056 | result = [] |
||
1057 | for f in fields(obj): |
||
1058 | value = _astuple_inner(getattr(obj, f.name), tuple_factory) |
||
1059 | result.append(value) |
||
1060 | return tuple_factory(result) |
||
1061 | elif isinstance(obj, (list, tuple)): |
||
1062 | return type(obj)(_astuple_inner(v, tuple_factory) for v in obj) |
||
1063 | elif isinstance(obj, dict): |
||
1064 | return type(obj)((_astuple_inner(k, tuple_factory), _astuple_inner(v, tuple_factory)) |
||
1065 | for k, v in obj.items()) |
||
1066 | else: |
||
1067 | return copy.deepcopy(obj) |
||
1068 | |||
1069 | |||
1070 | def make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True, |
||
1071 | repr=True, eq=True, order=False, unsafe_hash=False, |
||
1072 | frozen=False): |
||
1073 | """Return a new dynamically created dataclass. |
||
1074 | |||
1075 | The dataclass name will be 'cls_name'. 'fields' is an iterable |
||
1076 | of either (name), (name, type) or (name, type, Field) objects. If type is |
||
1077 | omitted, use the string 'typing.Any'. Field objects are created by |
||
1078 | the equivalent of calling 'field(name, type [, Field-info])'. |
||
1079 | |||
1080 | C = make_dataclass('C', ['x', ('y', int), ('z', int, field(init=False))], bases=(Base,)) |
||
1081 | |||
1082 | is equivalent to: |
||
1083 | |||
1084 | @dataclass |
||
1085 | class C(Base): |
||
1086 | x: 'typing.Any' |
||
1087 | y: int |
||
1088 | z: int = field(init=False) |
||
1089 | |||
1090 | For the bases and namespace parameters, see the builtin type() function. |
||
1091 | |||
1092 | The parameters init, repr, eq, order, unsafe_hash, and frozen are passed to |
||
1093 | dataclass(). |
||
1094 | """ |
||
1095 | |||
1096 | if namespace is None: |
||
1097 | namespace = {} |
||
1098 | else: |
||
1099 | # Copy namespace since we're going to mutate it. |
||
1100 | namespace = namespace.copy() |
||
1101 | |||
1102 | # While we're looking through the field names, validate that they |
||
1103 | # are identifiers, are not keywords, and not duplicates. |
||
1104 | seen = set() |
||
1105 | anns = {} |
||
1106 | for item in fields: |
||
1107 | if isinstance(item, str): |
||
1108 | name = item |
||
1109 | tp = 'typing.Any' |
||
1110 | elif len(item) == 2: |
||
1111 | name, tp, = item |
||
1112 | elif len(item) == 3: |
||
1113 | name, tp, spec = item |
||
1114 | namespace[name] = spec |
||
1115 | else: |
||
1116 | raise TypeError(f'Invalid field: {item!r}') |
||
1117 | |||
1118 | if not isinstance(name, str) or not name.isidentifier(): |
||
1119 | raise TypeError(f'Field names must be valid identifiers: {name!r}') |
||
1120 | if keyword.iskeyword(name): |
||
1121 | raise TypeError(f'Field names must not be keywords: {name!r}') |
||
1122 | if name in seen: |
||
1123 | raise TypeError(f'Field name duplicated: {name!r}') |
||
1124 | |||
1125 | seen.add(name) |
||
1126 | anns[name] = tp |
||
1127 | |||
1128 | namespace['__annotations__'] = anns |
||
1129 | # We use `types.new_class()` instead of simply `type()` to allow dynamic creation |
||
1130 | # of generic dataclassses. |
||
1131 | cls = types.new_class(cls_name, bases, {}, lambda ns: ns.update(namespace)) |
||
1132 | return dataclass(cls, init=init, repr=repr, eq=eq, order=order, |
||
1133 | unsafe_hash=unsafe_hash, frozen=frozen) |
||
1134 | |||
1135 | |||
1136 | def replace(obj, **changes): |
||
1137 | """Return a new object replacing specified fields with new values. |
||
1138 | |||
1139 | This is especially useful for frozen classes. Example usage: |
||
1140 | |||
1141 | @dataclass(frozen=True) |
||
1142 | class C: |
||
1143 | x: int |
||
1144 | y: int |
||
1145 | |||
1146 | c = C(1, 2) |
||
1147 | c1 = replace(c, x=3) |
||
1148 | assert c1.x == 3 and c1.y == 2 |
||
1149 | """ |
||
1150 | |||
1151 | # We're going to mutate 'changes', but that's okay because it's a |
||
1152 | # new dict, even if called with 'replace(obj, **my_changes)'. |
||
1153 | |||
1154 | if not _is_dataclass_instance(obj): |
||
1155 | raise TypeError("replace() should be called on dataclass instances") |
||
1156 | |||
1157 | # It's an error to have init=False fields in 'changes'. |
||
1158 | # If a field is not in 'changes', read its value from the provided obj. |
||
1159 | |||
1160 | for f in getattr(obj, _FIELDS).values(): |
||
1161 | # Only consider normal fields or InitVars. |
||
1162 | if f._field_type is _FIELD_CLASSVAR: |
||
1163 | continue |
||
1164 | |||
1165 | if not f.init: |
||
1166 | # Error if this field is specified in changes. |
||
1167 | if f.name in changes: |
||
1168 | raise ValueError(f'field {f.name} is declared with ' |
||
1169 | 'init=False, it cannot be specified with ' |
||
1170 | 'replace()') |
||
1171 | continue |
||
1172 | |||
1173 | if f.name not in changes: |
||
1174 | if f._field_type is _FIELD_INITVAR: |
||
1175 | raise ValueError(f"InitVar {f.name!r} " |
||
1176 | 'must be specified with replace()') |
||
1177 | changes[f.name] = getattr(obj, f.name) |
||
1178 | |||
1179 | # Create the new object, which calls __init__() and |
||
1180 | # __post_init__() (if defined), using all of the init fields we've |
||
1181 | # added and/or left in 'changes'. If there are values supplied in |
||
1182 | # changes that aren't fields, this will correctly raise a |
||
1183 | # TypeError. |
||
1184 | return obj.__class__(**changes) |
||
1185 |