Adding documentation to CWE-595 as part of #531 #619
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Signed-off-by: edanhub <[email protected]>
myteron
reviewed
Sep 19, 2024
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| # CWE-595: Comparison of Object References Instead of Object Contents | |||
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| In Python, the == operator is implemented by the `__eq__` method on an object [[python.org data model 2023](https://docs.python.org/3/reference/datamodel.html?highlight=__eq__#object.__eq__)]. For built-in types like `int` and `str`, the comparison is implemented in the interpreter. The main issue comes when implementing custom classes, where the default implementation compares object references using the `is` operator. The `is` operator compares the identities of the objects, equivalent to `id(obj1) == id(obj2)`. The `id` function is built into Python, and in the CPython interpreter, the standard implementation, it returns the object's memory address [[de Langen 2023](https://realpython.com/python-is-identity-vs-equality/)]. | |||
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| ## Non-Compliant Code Example | ||
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| The non-compliant code shows how the default comparison operator compares object references rather than the object values. Furthermore, it displays how this causes issues when comparing lists of objects, although it applies to other types of collections as well. Finally, it shows how the `in` operator also depends on the behavior of the `__eq__` method and, therefore, also returns a non-desirable result. |
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The noncompliant01.py
further down typo in should be int
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| The non-compliant code shows how the default comparison operator compares object references rather than the object values. Furthermore, it displays how this causes issues when comparing lists of objects, although it applies to other types of collections as well. Finally, it shows how the `in` operator also depends on the behavior of the `__eq__` method and, therefore, also returns a non-desirable result. | ||
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| [*noncompliant01.py:*](noncompliant01.py) |
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add the following to all source code files;
# SPDX-FileCopyrightText: OpenSSF project contributors
# SPDX-License-Identifier: MIT
Only needs to be in the files, not in the readme.md.
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Adding documentation to CWE-595 as part of #531