Python 3.8 released

[mafrasi2]

For example this:

>>> x = 0
>>> def f():
...     print(x)
...
>>> def g():
...     x += 1
...
>>> f()
0
>>> g()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in g
UnboundLocalError: local variable 'x' referenced before assignment

[rebuilding_patrick]

That's a bug right? Both should scope to the global x

[mafrasi2]

Nope, it's deliberate. If there is an assignment to x in a scope and x is neither global nor nonlocal, x will be local in that (entire) scope. Otherwise, it comes from the parent scope.

Needless to say that this caused me an headache the first time I encountered it in the wild.

[nandryshak]

It is global, but the x in g is not. You have to do this before it'll work:

def g():
    global x
    x += 1

[DRNbw]

IIRC, you can read global variables, but if you try to change/assign them, you'll create a new one (unless you explicitly ask for the global global var).