58 lines
1.8 KiB
Plaintext
58 lines
1.8 KiB
Plaintext
Importing every public name from a module using a wildcard (`+from mymodule import *+`) is a bad idea because:
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* It could lead to conflicts between names defined locally and the ones imported.
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* It reduces code readability as developers will have a hard time knowing where names come from.
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* It clutters the local namespace, which makes debugging more difficult.
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Remember that imported names can change when you update your dependencies. A wildcard import which works today might be broken tomorrow.
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There are two ways to avoid a wildcard import:
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* Replace it with `+import mymodule+` and access module members as `+mymodule.myfunction+`. If the module name is too long, alias it to a shorter name. Example: `+import pandas as pd+`
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* List every imported name. If necessary import statements can be split on multiple lines using parentheses (preferred solution) or backslashes.
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== Noncompliant Code Example
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----
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from math import * # Noncompliant
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def exp(x):
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pass
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print(exp(0)) # "None" will be printed
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----
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== Compliant Solution
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----
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import math
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def exp(x):
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pass
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print(math.exp(0)) # "1.0" will be printed
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----
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Or
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----
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from math import exp as m_exp
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def exp(x):
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pass
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print(m_exp(0)) # "1.0" will be printed
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----
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== Exceptions
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No issue will be raised in `+\_\_init\_\_.py+` files. Wildcard imports are a common way of populating these modules.
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No issue will be raised in modules doing only imports. Local modules are sometimes created as a proxy for third-party modules.
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----
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# file: mylibrary/pyplot.py
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try:
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from guiqwt.pyplot import * # Ok
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except Exception:
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from matplotlib.pyplot import * # Ok
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----
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Just keep in mind that wildcard imports might still create issues in these cases. It's always better to import only what you need.
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== See
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* https://docs.python.org/3.8/reference/simple_stmts.html#import[Python documentation - The import statement]
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