Inline Immediately Returned Variables

Sourcery refactoring id: inline-immediately-returned-variable

Description

Inlines a variable to a return in the case when the variable being declared is immediately returned

Before

def state_attributes(self):
    """Return the state attributes."""
    state_attr = {
        ATTR_CODE_FORMAT: self.code_format,
        ATTR_CHANGED_BY: self.changed_by,
    }
    return state_attr

After

def state_attributes(self):
    """Return the state attributes."""
    return {
        ATTR_CODE_FORMAT: self.code_format,
        ATTR_CHANGED_BY: self.changed_by,
    }

Explanation

Something that we often see in people’s code is assigning to a result variable and then immediately returning it.

Returning the result directly shortens the code and removes an unnecessary variable, reducing the mental load of reading the function.

Where intermediate variables can be useful is if they then get used as a parameter or a condition, and the name can act like a comment on what the variable represents. In the case where you’re returning it from a function, the function name is there to tell you what the result is - in the example above it’s the state attributes, and the state_attr name wasn’t providing any extra information.

One point to note is that if the variable has a type annotation, we will not suggest inlining it, since this would lose that information, possibly leading to type checking errors.

Related refactorings

• inline-immediately-yielded-variable