rspec/rules/S2208/python/rule.adoc

Importing every public name from a module using a wildcard (``++from mymodule import *++``) is a bad idea because:

* It could lead to conflicts between names defined locally and the ones imported.
* It reduces code readability as developers will have a hard time knowing where names come from.
* It clutters the local namespace, which makes debugging more difficult.

Remember that imported names can change when you update your dependencies. A wildcard import which works today might be broken tomorrow.

There are two ways to avoid a wildcard import:

* 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++``
* List every imported name. If necessary import statements can be split on multiple lines using parentheses (preferred solution) or backslashes.

== Noncompliant Code Example

----
from math import *  # Noncompliant
def exp(x):
    pass
print(exp(0))   # "None" will be printed
----

== Compliant Solution

----
import math
def exp(x):
    pass
print(math.exp(0))   # "1.0" will be printed
----
Or

----
from math import exp as m_exp
def exp(x):
    pass
print(m_exp(0))   # "1.0" will be printed
----

== Exceptions

No issue will be raised in ``++__init__.py++`` files. Wildcard imports are a common way of populating these modules.
No issue will be raised in modules doing only imports. Local modules are sometimes created as a proxy for third-party modules.

----
# file: mylibrary/pyplot.py
try:
    from guiqwt.pyplot import *  # Ok
except Exception:
    from matplotlib.pyplot import *  # Ok
----

Just keep in mind that wildcard imports might still create issues in these cases. It's always better to import only what you need.

== See

* https://docs.python.org/3.8/reference/simple_stmts.html#import[Python documentation - The import statement]