[Adjust Rule] Remove SIM116 due to inefficiency/code evaluation problem

[Effervex]

Desired change

• Rule(s): SIM116
• Adjustment: Remove the enforcement of the rule #31

Explanation

This style guideline may result in better looking code, but it is inefficient and can even create errors. Each dict value is interpreted whenever the dict is evaluated.

Example

some_array = [0,1] if x else [0,1,2]
mapping = {
  "foo": "bar",
  "foo2": long_expensive_function()
  "foo3": three_arg_func(some_array[0], some_array[1], some_array[2])
}
return mapping.get("foo",42) # This will still evaluate "foo2", and if x is True, completely crash when evaluating "foo3"

[MartinThoma]

thank you for the explanation - I understand that function calls might be problematic. My plan now is to only show this message if the values of mapping are constants. If at least one argument is a function, SIM116 should not be shown.

[Effervex]

That's a nice solution! I didn't think that level of detail could be checked, but that's useful.

[MartinThoma]

This is an example of a false-positive:

if a == "foo":
    return "bar"
elif a == "bar":
    return baz() # <----- that makes it a false-positive
elif a == "boo":
    return "ooh"
else:
    return 42

Here is its AST:

$ python -m astpretty --no-show-offsets /dev/stdin <<< `cat example.py`
Module(
    body=[
        If(
            test=Compare(
                left=Name(id='a', ctx=Load()),
                ops=[Eq()],
                comparators=[Constant(value='foo', kind=None)],
            ),
            body=[
                Return(
                    value=Constant(value='bar', kind=None),
                ),
            ],
            orelse=[
                If(
                    test=Compare(
                        left=Name(id='a', ctx=Load()),
                        ops=[Eq()],
                        comparators=[Constant(value='bar', kind=None)],
                    ),
                    body=[
                        Return(
                            value=Call(
                                func=Name(id='baz', ctx=Load()),
                                args=[],
                                keywords=[],
                            ),
                        ),
                    ],
                    orelse=[
                        If(
                            test=Compare(
                                left=Name(id='a', ctx=Load()),
                                ops=[Eq()],
                                comparators=[Constant(value='boo', kind=None)],
                            ),
                            body=[
                                Return(
                                    value=Constant(value='ooh', kind=None),
                                ),
                            ],
                            orelse=[
                                Return(
                                    value=Constant(value=42, kind=None),
                                ),
                            ],
                        ),
                    ],
                ),
            ],
        ),
    ],
    type_ignores=[],
)