Having only function, module, class, generator, etc. scope in Python before this PEP might have made sense, but they really should have added pattern matching scope to keep things sane here.

There are some exceptions to this - for example, the iteration variable(s) in a list comprehension are only in scope within the comprehension.

Worth noting that this was _fixed_ in Python 3.

In Python 2.7 you get this:

    >>> my_list = [x for x in 'hello']
    >>> x
    'o'

Thanks, I didn't realize that. That makes their choice really baffling.

The explanation is that (in Python 3) list comprehensions are really just syntactic sugar for generator expressions. In Python, "scope" is really a synonym for "dictionary attached to some object", so generators can have local variables (since they have their own internal scope), but purely syntactic constructs cannot.

and class scope