ElementCallable.make() - Code Metrics - Inspection of "Merge pull request #35 from sprout42/callables" - sprout42/StarStruct - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 5c1426...4ae943 )

by Aaron

created 2016-11-30 21:56 UTC

ElementCallable.make() F

↳ Parent: ElementCallable

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	9
c	1
b	0
f	0
dl	0
loc	33
rs	3

"""
Element callable.

Call a function to validate data.

.. code-block:: python

    from binascii import crc32

    ExampleMessage = Message('VarTest', [('x', 'B'), ('y', 'B')])

    CRCedMessage = Message('CRCedMessage', [
       ('data', ExampleMessage),                    # A data field that has the example message in it
       ('crc', 'I', crc32, ['data']),               # Crc the data, and give an error if we have something unexpected
       ('crc', 'I', crc32, ['data'], False),        # Crc the data, but don't give an error
   ])

Following creating this message, you have two options:

1. Specify a value. The function will be used to validate the value.

.. code-block:: python

    def adder(x, y):
        return x + y

    AdderMessage = Message('AdderMessage', [
        ('item_a', 'H'),
        ('item_b', 'B'),
        ('function_data', 'I', adder, ['item_a', 'item_b']),
    ])

    test_data = {
        'item_a': 2,
        'item_b': 5,
        'function_data': 7,
    }

    made = AdderMessage.make(test_data)
    assert made.item_a == 2
    assert made.item_b == 5
    assert made.function_data == 7

    # If you specify the wrong value, you'll get a ValueError
    test_data = {
        'item_a': 2,
        'item_b': 5,
        'function_data': 33,
    }

    try:
        made = AdderMessage.make(test_data)
    except ValueError:
        print('Told you so')

    # Unless you specify `False` in your original item, then
    # nobody will care.

2. Use the function to generate a value.

.. code-block:: python

    def adder(x, y):
        return x + y

    AdderMessage = Message('AdderMessage', [
        ('item_a', 'H'),
        ('item_b', 'B'),
        ('function_data', 'I', adder, ['item_a', 'item_b']),
    ])

    test_data = {
        'item_a': 2,
        'item_b': 5,
    }

    made = AdderMessage.make(test_data)
    assert made.item_a == 2
    assert made.item_b == 5
    assert made.function_data == 7

"""

import copy
import struct

from typing import Optional
# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3

from starstruct.element import register, Element
from starstruct.modes import Mode


@register

class ElementCallable(Element):
    """
    Initialize a StarStruct element object.

    :param field: The fields passed into the constructor of the element
    :param mode: The mode in which to pack the bytes
    :param alignment: Number of bytes to align to
    """
    def __init__(self, field: list, mode: Optional[Mode]=Mode.Native, alignment: Optional[int]=1):
        # All of the type checks have already been performed by the class
        # factory
        self.name = field[0]

        # Callable elements use the normal struct packing method
        self.format = field[1]
        self._func_ref = field[2]
        self._func_args = field[3]

        if len(field) == 5:
            self._error_on_bad_result = field[4]
        else:
            self._error_on_bad_result = True

        self.update(mode, alignment)

    @property
    def _struct(self):
        return struct.Struct(self._mode.value + self.format)

    @staticmethod
    def valid(field: tuple) -> bool:
        """
        See :py:func:`starstruct.element.Element.valid`

        :param field: The items to determine the structure of the element
        """
        return len(field) >= 4 \
            and isinstance(field[0], str) \
            and isinstance(field[1], str) \
            and callable(field[2]) \
            and isinstance(field[3], list)

    def validate(self, msg):
        """
        Ensure that the supplied message contains the required information for
        this element object to operate.

        All elements that are Variable must reference valid Length elements.
        """
        # TODO: Validate the object
        self._elements = msg
class Foo:
    def __init__(self, x=None):
        self.x = x

        if not all(k in msg
                   for k in [arg if isinstance(arg, str) else arg.decode('utf-8')
                             for arg in self._func_args]):
            raise ValueError('Need all keys to be in the message')

        pass


    def update(self, mode=None, alignment=None):
        """change the mode of the struct format"""
        if mode:
            self._mode = mode

        if alignment:
            self._alignment = alignment

    def pack(self, msg):
        """Pack the provided values into the supplied buffer."""
        return self._struct.pack(self.make(msg))

    def unpack(self, msg, buf):
        """Unpack data from the supplied buffer using the initialized format."""
        ret = self._struct.unpack_from(buf)
        if isinstance(ret, (list, tuple)):
            # TODO: I don't know if there is a case where we want to keep
            # it as a list... but for now I'm just going to do this
            ret = ret[0]

        # Only check for errors if they haven't told us not to
        if self._error_on_bad_result:
            # Pretend we're getting a dictionary to make our item,
            # but it has no reference to `self`. This is so we check
            # for errors correctly.
            temp_dict = copy.deepcopy(msg._asdict())
            temp_dict.pop(self.name)
            expected_value = self.make(temp_dict)

            # Check for an error
            if expected_value != ret:
                raise ValueError('Expected value was: {0}, but got: {1}'.format(
                    expected_value,
                    ret,
                ))

        return (ret, buf[self._struct.size:])

    def make(self, msg):
        """Return the expected "made" value"""
        # If we aren't going to error on a bad result
        # and our name is in the message, just send the value
        # No need to do extra work.
        if not self._error_on_bad_result \
                and self.name in msg \
                and msg[self.name] is not None:
            return msg[self.name]

        items = []

        for reference in self._func_args:
            if isinstance(reference, str):
                index = reference
                attr = 'make'
            elif isinstance(reference, bytes):
                index = reference.decode('utf-8')
                attr = 'pack'
            else:
                raise ValueError('Needed str or bytes for the reference')

            items.append(
                getattr(self._elements[index], attr)(msg)
            )

        ret = self._func_ref(*items)


        if self.name in msg:
            if ret != msg[self.name]:
                raise ValueError('Excepted value: {0}, but got: {1}'.format(ret, msg[self.name]))

        return ret


Push — master ( 5c1426...4ae943 )

ElementCallable.make() F

Complexity

Size

Duplication

Importance

1. Missing Dependencies

2. Missing init.py files

1			"""
2			Element callable.
3
4			Call a function to validate data.
5
6			.. code-block:: python
7
8			from binascii import crc32
9
10			ExampleMessage = Message('VarTest', [('x', 'B'), ('y', 'B')])
11
12			CRCedMessage = Message('CRCedMessage', [
13			('data', ExampleMessage), # A data field that has the example message in it
14			('crc', 'I', crc32, ['data']), # Crc the data, and give an error if we have something unexpected
15			('crc', 'I', crc32, ['data'], False), # Crc the data, but don't give an error
16			])
17
18			Following creating this message, you have two options:
19
20			1. Specify a value. The function will be used to validate the value.
21
22			.. code-block:: python
23
24			def adder(x, y):
25			return x + y
26
27			AdderMessage = Message('AdderMessage', [
28			('item_a', 'H'),
29			('item_b', 'B'),
30			('function_data', 'I', adder, ['item_a', 'item_b']),
31			])
32
33			test_data = {
34			'item_a': 2,
35			'item_b': 5,
36			'function_data': 7,
37			}
38
39			made = AdderMessage.make(test_data)
40			assert made.item_a == 2
41			assert made.item_b == 5
42			assert made.function_data == 7
43
44			# If you specify the wrong value, you'll get a ValueError
45			test_data = {
46			'item_a': 2,
47			'item_b': 5,
48			'function_data': 33,
49			}
50
51			try:
52			made = AdderMessage.make(test_data)
53			except ValueError:
54			print('Told you so')
55
56			# Unless you specify `False` in your original item, then
57			# nobody will care.
58
59			2. Use the function to generate a value.
60
61			.. code-block:: python
62
63			def adder(x, y):
64			return x + y
65
66			AdderMessage = Message('AdderMessage', [
67			('item_a', 'H'),
68			('item_b', 'B'),
69			('function_data', 'I', adder, ['item_a', 'item_b']),
70			])
71
72			test_data = {
73			'item_a': 2,
74			'item_b': 5,
75			}
76
77			made = AdderMessage.make(test_data)
78			assert made.item_a == 2
79			assert made.item_b == 5
80			assert made.function_data == 7
81
82			"""
83
84			import copy
85			import struct
86
87			from typing import Optional
			0 ignored issues – show Configuration introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report The import `typing` could not be resolved. This can be caused by one of the following: 1. Missing Dependencies This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands. # .scrutinizer.yml before_commands: - sudo pip install abc # Python2 - sudo pip3 install abc # Python3 Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version. 2. Missing __init__.py files This error could also result from missing `__init__.py` files in your module folders. Make sure that you place one file in each sub-folder. Loading history...
88
89			from starstruct.element import register, Element
90			from starstruct.modes import Mode
91
92
93			@register
			0 ignored issues – show best-practice introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report Too many instance attributes (8/7) Loading history...
94			class ElementCallable(Element):
95			"""
96			Initialize a StarStruct element object.
97
98			:param field: The fields passed into the constructor of the element
99			:param mode: The mode in which to pack the bytes
100			:param alignment: Number of bytes to align to
101			"""
102			def __init__(self, field: list, mode: Optional[Mode]=Mode.Native, alignment: Optional[int]=1):
103			# All of the type checks have already been performed by the class
104			# factory
105			self.name = field[0]
106
107			# Callable elements use the normal struct packing method
108			self.format = field[1]
109			self._func_ref = field[2]
110			self._func_args = field[3]
111
112			if len(field) == 5:
113			self._error_on_bad_result = field[4]
114			else:
115			self._error_on_bad_result = True
116
117			self.update(mode, alignment)
118
119			@property
120			def _struct(self):
121			return struct.Struct(self._mode.value + self.format)
122
123			@staticmethod
124			def valid(field: tuple) -> bool:
125			"""
126			See :py:func:`starstruct.element.Element.valid`
127
128			:param field: The items to determine the structure of the element
129			"""
130			return len(field) >= 4 \
131			and isinstance(field[0], str) \
132			and isinstance(field[1], str) \
133			and callable(field[2]) \
134			and isinstance(field[3], list)
135
136			def validate(self, msg):
137			"""
138			Ensure that the supplied message contains the required information for
139			this element object to operate.
140
141			All elements that are Variable must reference valid Length elements.
142			"""
143			# TODO: Validate the object
144			self._elements = msg
			0 ignored issues – show Coding Style introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report The attribute `_elements` was defined outside `__init__`. It is generally a good practice to initialize all attributes to default values in the `__init__` method: class Foo: def __init__(self, x=None): self.x = x Loading history...
145
146			if not all(k in msg
147			for k in [arg if isinstance(arg, str) else arg.decode('utf-8')
148			for arg in self._func_args]):
149			raise ValueError('Need all keys to be in the message')
150
151			pass
			0 ignored issues – show Unused Code introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report Unnecessary pass statement Loading history...
152
153			def update(self, mode=None, alignment=None):
154			"""change the mode of the struct format"""
155			if mode:
156			self._mode = mode
157
158			if alignment:
159			self._alignment = alignment
160
161			def pack(self, msg):
162			"""Pack the provided values into the supplied buffer."""
163			return self._struct.pack(self.make(msg))
164
165			def unpack(self, msg, buf):
166			"""Unpack data from the supplied buffer using the initialized format."""
167			ret = self._struct.unpack_from(buf)
168			if isinstance(ret, (list, tuple)):
169			# TODO: I don't know if there is a case where we want to keep
170			# it as a list... but for now I'm just going to do this
171			ret = ret[0]
172
173			# Only check for errors if they haven't told us not to
174			if self._error_on_bad_result:
175			# Pretend we're getting a dictionary to make our item,
176			# but it has no reference to `self`. This is so we check
177			# for errors correctly.
178			temp_dict = copy.deepcopy(msg._asdict())
179			temp_dict.pop(self.name)
180			expected_value = self.make(temp_dict)
181
182			# Check for an error
183			if expected_value != ret:
184			raise ValueError('Expected value was: {0}, but got: {1}'.format(
185			expected_value,
186			ret,
187			))
188
189			return (ret, buf[self._struct.size:])
190
191			def make(self, msg):
192			"""Return the expected "made" value"""
193			# If we aren't going to error on a bad result
194			# and our name is in the message, just send the value
195			# No need to do extra work.
196			if not self._error_on_bad_result \
197			and self.name in msg \
198			and msg[self.name] is not None:
199			return msg[self.name]
200
201			items = []
202
203			for reference in self._func_args:
204			if isinstance(reference, str):
205			index = reference
206			attr = 'make'
207			elif isinstance(reference, bytes):
208			index = reference.decode('utf-8')
209			attr = 'pack'
210			else:
211			raise ValueError('Needed str or bytes for the reference')
212
213			items.append(
214			getattr(self._elements[index], attr)(msg)
215			)
216
217			ret = self._func_ref(*items)
			0 ignored issues – show Coding Style introduced 2016-11-30 19:25 UTC by Report Bug Copy Issue Report Usage of `` or `` arguments should usually be done with care. Generally, there is nothing wrong with usage of `` or `**` arguments. For readability of the code base, we suggest to not over-use these language constructs though. For more information, we can recommend this blog post from Ned Batchelder including its comments which also touches this aspect. Loading history...
218
219			if self.name in msg:
220			if ret != msg[self.name]:
221			raise ValueError('Excepted value: {0}, but got: {1}'.format(ret, msg[self.name]))
222
223			return ret
224

sprout42 / StarStruct

Push — master ( 5c1426...4ae943 )

ElementCallable.make() F

Complexity

Size

Duplication

Importance

1. Missing Dependencies

2. Missing __init__.py files

Duplication Side-by-Side

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2. Missing init.py files