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""" |
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Provides extra ready-to-use classes for constructing custom constants. |
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""" |
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import operator |
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from .core import Constants |
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from .core import SimpleConstant |
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from .exceptions import CandvValueNotFoundError |
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from ._utils import export |
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@export |
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class VerboseMixin: |
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""" |
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Adds ``verbose_name`` and ``help_text`` attributes to constants. |
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Arguments must be passed as kwargs. |
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:argument str verbose_name: optional verbose name |
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:argument str help_text: optional description |
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**Example**: |
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.. code-block:: python |
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class CustomConstant(object): |
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def __init__(self, arg1, arg2, kwarg1=None): |
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pass |
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class VerboseCustomConstant(VerboseMixin, CustomConstant): |
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def __init__(self, arg1, arg2, kwarg1=None, verbose_name=None, help_text=None): |
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super().__init__( |
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arg1, |
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arg2, |
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kwarg1=kwarg1, |
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verbose_name=verbose_name, |
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help_text=help_text, |
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) |
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""" |
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def __init__(self, *args, **kwargs): |
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self.verbose_name = kwargs.pop('verbose_name', None) |
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self.help_text = kwargs.pop('help_text', None) |
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super().__init__(*args, **kwargs) |
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def merge_into_group(self, group): |
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""" |
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Overrides :meth:`~candv.base.Constant.merge_into_group` to add |
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``verbose_name`` with ``help_text`` attributes to the target group. |
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""" |
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super().merge_into_group(group) |
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group.verbose_name = self.verbose_name |
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group.help_text = self.help_text |
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def to_primitive(self, *args, **kwargs): |
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""" |
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.. versionchanged:: 1.5.0 |
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The ``context`` param is replaced by ``*args`` and ``**kwargs``. |
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.. versionadded:: 1.3.0 |
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""" |
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primitive = super().to_primitive(*args, **kwargs) |
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primitive.update({ |
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'verbose_name': ( |
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str(self.verbose_name) |
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if self.verbose_name is not None |
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else None |
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), |
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'help_text': ( |
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str(self.help_text) |
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if self.help_text is not None |
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else None |
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), |
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}) |
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return primitive |
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@export |
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class VerboseConstant(VerboseMixin, SimpleConstant): |
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""" |
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A constant with optional verbose name and optional help text. |
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:argument str verbose_name: optional verbose name of the constant |
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:argument str help_text: optional description of the constant |
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:ivar str verbose_name: verbose name of the constant. Default: ``None`` |
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:ivar str help_text: verbose description of the constant. Default: ``None`` |
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""" |
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def __init__(self, verbose_name=None, help_text=None): |
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super().__init__(verbose_name=verbose_name, help_text=help_text) |
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@export |
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class ValueConstant(SimpleConstant): |
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""" |
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A constant with ability to hold arbitrary values. |
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:argument value: a value to attach to constant |
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:ivar value: constant's value |
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""" |
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def __init__(self, value): |
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super().__init__() |
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self.value = value |
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def merge_into_group(self, group): |
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""" |
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Redefines :meth:`~candv.base.Constant.merge_into_group` and adds ``value`` |
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attribute to the target group. |
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""" |
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super().merge_into_group(group) |
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group.value = self.value |
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def to_primitive(self, *args, **kwargs): |
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""" |
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.. versionchanged:: 1.5.0 |
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The ``context`` param is replaced by ``*args`` and ``**kwargs``. |
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.. versionadded:: 1.3.0 |
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""" |
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primitive = super().to_primitive(*args, **kwargs) |
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value = self.value |
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if hasattr(value, "isoformat"): |
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value = value.isoformat() |
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if hasattr(value, "to_primitive"): |
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value = value.to_primitive(*args, **kwargs) |
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elif callable(value): |
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value = value() |
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primitive['value'] = value |
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return primitive |
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@export |
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class VerboseValueConstant(VerboseMixin, ValueConstant): |
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""" |
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A constant which can have both verbose name, help text, and a value. |
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:argument value: a value to attach to the constant |
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:argument str verbose_name: an optional verbose name of the constant |
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:argument str help_text: an optional description of the constant |
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:ivar value: constant's value |
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:ivar str verbose_name: verbose name of the constant. Default: ``None`` |
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:ivar str help_text: verbose description of the constant. Default: ``None`` |
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""" |
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def __init__(self, value, verbose_name=None, help_text=None): |
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super().__init__(value, verbose_name=verbose_name, help_text=help_text) |
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@export |
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class Values(Constants): |
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""" |
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A container for :class:`ValueConstant` and its derivatives. |
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Supports getting and filtering constants by their values plus listing values |
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of all constants in container. |
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""" |
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constant_class = ValueConstant |
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@classmethod |
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def get_by_value(cls, value): |
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""" |
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Get a constant by its value. |
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:param value: value of the constant to look for |
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:returns: first found constant with given value |
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:raises CandvValueNotFoundError: if no constant in container has given value |
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""" |
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for constant in cls.iterconstants(): |
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if constant.value == value: |
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return constant |
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raise CandvValueNotFoundError( |
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"constant with value \"{0}\" is not present in \"{1}\"" |
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.format(value, cls) |
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) |
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@classmethod |
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def filter_by_value(cls, value): |
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""" |
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Get all constants which have given value. |
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:param value: value of the constants to look for |
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:returns: list of all found constants with given value |
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""" |
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constants = [] |
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for constant in cls.iterconstants(): |
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if constant.value == value: |
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constants.append(constant) |
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return constants |
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@classmethod |
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def values(cls): |
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""" |
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List values of all constants in the order they were defined. |
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:returns: :class:`list` of values |
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**Example**: |
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.. code-block:: python |
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from candv import Values |
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from candv import ValueConstant |
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class FOO(Values): |
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TWO = ValueConstant(2) |
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ONE = ValueConstant(1) |
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SOME = ValueConstant("some string") |
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.. code-block:: python |
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>>> FOO.values() |
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[2, 1, 'some string'] |
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.. note:: |
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Overrides :meth:`~candv.base.ConstantsContainer.values` since 1.1.2. |
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""" |
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return [ |
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x.value |
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for x in cls.iterconstants() |
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] |
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@classmethod |
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def itervalues(cls): |
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""" |
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Get an iterator over values of all constants in the order they were defined. |
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Same as :meth:`values` but returns an interator. |
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.. note:: |
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Overrides :meth:`~candv.base.ConstantsContainer.itervalues` since 1.1.2. |
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""" |
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return map(operator.attrgetter("value"), cls.iterconstants()) |
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