r2c-best-practices

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A collection of opinionated rules for best practices in popular languages. Recommended for users who want really strict coding standards.

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Rules (134)

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Function $F mutates default dict $D. Python only instantiates default function arguments once and shares the instance across the function calls. If the default function argument is mutated, that will modify the instance used by all future function calls. This can cause unexpected results, or lead to security vulnerabilities whereby one function consumer can view or modify the data of another function consumer. Instead, use a default argument (like None) to indicate that no argument was provided and instantiate a new dictionary at that time. For example: `if $D is None: $D = {}`.

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Function $F mutates default list $D. Python only instantiates default function arguments once and shares the instance across the function calls. If the default function argument is mutated, that will modify the instance used by all future function calls. This can cause unexpected results, or lead to security vulnerabilities whereby one function consumer can view or modify the data of another function consumer. Instead, use a default argument (like None) to indicate that no argument was provided and instantiate a new list at that time. For example: `if $D is None: $D = []`.

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Detected useless if statement. 'if (True)' and 'if (False)' always result in the same behavior, and therefore is not necessary in the code. Remove the 'if (False)' expression completely or just the 'if (True)' comparison depending on which expression is in the code.

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`$X == $X` or `$X != $X` is always true. (Unless the value compared is a float or double). To test if `$X` is not-a-number, use `Double.isNaN($X)`.

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Use `sys.exit` over the python shell `exit` built-in. `exit` is a helper for the interactive shell and may not be available on all Python implementations. https://stackoverflow.com/questions/6501121/difference-between-exit-and-sys-exit-in-python

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Detected a 'requests' call without a timeout set. By default, 'requests' calls wait until the connection is closed. This means a 'requests' call without a timeout will hang the program if a response is never received. Consider setting a timeout for all 'requests'.

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Use tempfile.NamedTemporaryFile instead. From the official Python documentation: THIS FUNCTION IS UNSAFE AND SHOULD NOT BE USED. The file name may refer to a file that did not exist at some point, but by the time you get around to creating it, someone else may have beaten you to the punch.

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Avoid using null on string-based fields such as CharField and TextField. If a string-based field has null=True, that means it has two possible values for "no data": NULL, and the empty string. In most cases, it's redundant to have two possible values for "no data;" the Django convention is to use the empty string, not NULL.

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Detected file permissions that are set to more than `0600` (user/owner can read and write). Setting file permissions to higher than `0600` is most likely unnecessary and violates the principle of least privilege. Instead, set permissions to be `0600` or less for os.Chmod, os.Mkdir, os.OpenFile, os.MkdirAll, and ioutil.WriteFile

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Detected useless comparison operation `$X == $X` or `$X != $X`. This will always return 'True' or 'False' and therefore is not necessary. Instead, remove this comparison operation or use another comparison expression that is not deterministic.

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Unsafe usage of mutable initializer with attr.s decorator. Multiple instances of this class will re-use the same data structure, which is likely not the desired behavior. Consider instead: replace assignment to mutable initializer (ex. dict() or {}) with attr.ib(factory=type) where type is dict, set, or list

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The string method replaceAll is not supported in all versions of javascript, and is not supported by older browser versions. Consider using replace() with a regex as the first argument instead like mystring.replace(/bad/g, "good") instead of mystring.replaceAll("bad", "good") (https://discourse.threejs.org/t/replaceall-is-not-a-function/14585)

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Detected a hidden goroutine. Function invocations are expected to synchronous, and this function will execute asynchronously because all it does is call a goroutine. Instead, remove the internal goroutine and call the function using 'go'.