What's the scope of a variable initialized in

Question

I'm new to Python, so this is probably a simple scoping question. The following code in a Python file (module) is confusing me slightly:

if __name__ == '__main__':
    x = 1

print x

In other languages I've worked in, this code would throw an exception, as the x variable is local to the if statement and should not exist outside of it. But this code executes, and prints 1. Can anyone explain this behavior? Are all variables created in a module global/available to the entire module?

Answer 1

As Eli said, Python doesn't require variable declaration. In C you would say:

int x;
if(something)
    x = 1;
else
    x = 2;

but in Python declaration is implicit, so when you assign to x it is automatically declared. It's because Python is dynamically typed - it wouldn't work in a statically typed language, because depending on the path used, a variable might be used without being declared. This would be caught at compile time in a statically typed language, but with a dynamically typed language it's allowed.

The only reason that a statically typed language is limited to having to declare variables outside of if statements in because of this problem. Embrace the dynamic!