About global declarations, Python Language Ref (PLR) explains:
[https://docs.python.org/3.4/reference/simple_stmts.html#the-global-statement]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Names listed in a global statement must not be used
in the same code block textually preceding that global statement.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
What I understand is that the following code is incorrect:
# ---------------------------------------
def f():
x=42
global x
f()
print(x)
# ---------------------------------------
And indeed, executing this piece of code "raises" a warning :
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.py:3: SyntaxWarning: name 'x' is assigned to before global declaration
global x
42
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Now, global declaration has another restriction, as PLR explains:
[https://docs.python.org/3.4/reference/simple_stmts.html#the-global-statement]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Names listed in a global statement must not be defined as formal parameters
or in a for loop control target,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
What I understand is that the following is a must-not-code:
# ---------------------------------------
def f():
global i
for i in range(1,3):
print(10*i)
f()
print(i)
# ---------------------------------------
But, the later code executes silently without any warning:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
10
20
2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So my question is: what is the restriction about global as loop control
variable the docs is referring to?
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