Python scopes and namespaces

Python Tutorial - scopes and namespaces

This stuff is possible:

1
2
3
4
5
6
7
8
9

if True:
    a = 10

print(a)

for i in range(1):
    wat = "wat"

print(wat)

1
2
3
4
5
6
7

global_foo = 42

def foo_changer():
    global_foo = 123

foo_changer()
print(global_foo)  # 42

global_foo here is not being assigned. Instead, a local variable is created and assigned. See also global and nonlocal statements.

A special quirk of Python is that – if no global or nonlocal statement is in effect – assignments to names always go into the innermost scope. Assignments do not copy data — they just bind names to objects. The same is true for deletions: the statement del x removes the binding of x from the namespace referenced by the local scope. In fact, all operations that introduce new names use the local scope: in particular, import statements and function definitions bind the module or function name in the local scope.

But you should avoid code like this anyway.