Function Attribute / Global Variable Confusion

[digitalmatic7]

Function attributes and global variables seem quite similar:

def hi():

    hi.bye = 50     # function attribute

hi()

def testing():

    global ok       # global variable
    ok = 50

testing()

print(hi.bye + ok)  # output -> 100 

Can someone explain what the main difference is between the two?

Also PyCharm gives me two warnings in the editor (no errors in output area):

"Global variable 'ok' is undefined at the module level"

"Cannot find reference 'bye' in 'function'"

[DeaD_EyE]

This is not possible, because the function object is first evaluated and then the function object which sits somewhere in memory is assigned to the name hi. Inside the function you try to set an attribute on an reference which does not exist.

def hi():
    hi.bye = 50

You can do instead:

def hi():
    pass
hi.bye = 50
print(hi.bye)

In this case the function is created and assigned to the name hi.
Afterwards the integer object with the value 50 is assigned to the function, which refers to the name hi. The dynamic behavior comes from the dict. Look into hi.__dict__ before assignment and after.


The use of global is often a marker for broken code.
Try to avoid it.

# ok does not exist

def testing():
    global ok
    ok = 50

# ok still does not exist.
# now calling the function

testing()

# ok exists now and has the value 50

Using this code style is like guessing. At some point in your program, you lose the overview when which name is assigned.

You should use functions as they made for.

def foo():
    return 42

def bar():
    return 1337

result = foo() + bar()
print(result)