PyCharm：在分配之前可能会在finally块中引用变量吗？

Question

PyCharm warns me that variable category can be referenced before assignment but I don't think so.

Except should catch every Exception (except fatal errors) and finally is called after try or except block.

    try:
        category = lst[2]
    except:
        category = None
    finally:
        if not category: #here
            category = self.default_category

What do you think? Is it true or is it a bug?

Answer 1

Perhaps PyCharm is seeing the assignment without considering, "assignment to what". That is, the None is what makes the difference, consider if you instead wrote:

try:
    category = lst[2]
except:
    category = Noone
finally:
    if not category:
        category = self.default_category

(Or None/1 , etc.) Then you'd get:

NameError: name 'category' is not defined

as there would be an exception in the exception if lst were empty:

When an exception has occurred in the try clause and has not been handled by an except clause (or it has occurred in an except or else clause), it is re-raised after the finally clause has been executed.