Python variable scope in if-statements [duplicate]

Answer 1

if statements don't define a scope in Python.

Neither do loops, with statements, try / except, etc.

Only modules, functions and classes define scopes.

See Python Scopes and Namespaces in the Python Tutorial.

Answer 2

All python variables used in a function live in the function level scope. (ignoring global and closure variables)

It is useful in case like this:

if foo.contains('bar'):
   value = 2 + foo.count('b')
else:
   value = 0

That way I don't have to declare the variable before the if statement.

Answer 3

Yes, in Python, variable scopes inside if-statements are visible outside of the if-statement. Two related questions gave an interestion discussion:

Short Description of the Scoping Rules?

and

Python variable scope error