unnecessary-paren-on-raise-exception (RSE102)

Derived from the flake8-raise linter.

Fix is always available.

What it does

Checks for unnecessary parentheses on raised exceptions.

Why is this bad?

If an exception is raised without any arguments, parentheses are not required, as the raise statement accepts either an exception instance or an exception class (which is then implicitly instantiated).

Removing the parentheses makes the code more concise.

Known problems

Parentheses can only be omitted if the exception is a class, as opposed to a function call. This rule isn't always capable of distinguishing between the two.

For example, if you import a function module.get_exception from another module, and module.get_exception returns an exception object, this rule will incorrectly mark the parentheses in raise module.get_exception() as unnecessary.

Example

raise TypeError()

Use instead:

raise TypeError

References

• Python documentation: The raise statement