star-arg-unpacking-after-keyword-arg (B026)#
Derived from the flake8-bugbear linter.
What it does#
Checks for function calls that use star-argument unpacking after providing a keyword argument
Why is this bad?#
In Python, you can use star-argument unpacking to pass a list or tuple of arguments to a function.
Providing a star-argument after a keyword argument can lead to confusing behavior, and is only supported for backwards compatibility.
Example#
def foo(x, y, z):
return x, y, z
foo(1, 2, 3) # (1, 2, 3)
foo(1, *[2, 3]) # (1, 2, 3)
# foo(x=1, *[2, 3]) # TypeError
# foo(y=2, *[1, 3]) # TypeError
foo(z=3, *[1, 2]) # (1, 2, 3) # No error, but confusing!
Use instead:
def foo(x, y, z):
return x, y, z
foo(1, 2, 3) # (1, 2, 3)
foo(x=1, y=2, z=3) # (1, 2, 3)
foo(*[1, 2, 3]) # (1, 2, 3)
foo(*[1, 2], 3) # (1, 2, 3)