Python's braindamaged scoping rules
Python distinguishes between local and global variables from assignment statements. If a variable is assigned within a function, that variable is treated as a local variable. This means that you cannot do this:
my_var = None
def set_my_var():
my_var = "hello world"
set_my_var()
print my_var
As my_var is assigned within the function, it is treated as a local variable that is separate to the global variable with the same name. Instead, you have to explicitly tell the compiler that you want to assign the global variable, like this:
my_var = None
def set_my_var():
global my_var
my_var = "hello world"
set_my_var()
print my_var
This all strikes me as rather brain-damaged. If assignments are used to detect the declaration of a variable, is it really so difficult to just examine the surrounding context to see if there is already a variable with the same name?