These two keywords are used to change the scope of a previously declared variable. nolocal is often used when you need to access a variable in a nested function:
def func1():
x = 5
def func2():
nolocal x
print(x)
func2()
global is a more straightforward instruction. It makes a previously declared variable global. For example, consider this code:
x = 5
def func1():
print(x)
func1()
> 5
Since x is declared before function call, func1 can access it. However, if you try to change it:
x = 5
def func2():
x += 3
func2()
> UnboundLocalError: local variable 'c' referenced before assignment
To make it work, we need to indicate that by x we mean the global variable x:
x = 5
def func2():
global x
x += 3
func2()
What is the difference between classmethod and staticmethod?
Both of them define a class method that can be called without instantiating an object of the class. The only difference is in their signature:
class A:
@staticmethod
def func1():
pass
@classmethod
def func2(cls):
pass
As you can see, the classmethod accepts an implicit argument cls, which will be set to the class A itself. Once common use case for classmethod is creating alternative inheritable constructors.
