*Memo:
- My post explains global and nonlocal with 3 functions (1).
- My post explains global and nonlocal with 3 functions (2).
- My post explains global and nonlocal with 3 functions (3).
- My post explains global and nonlocal with 2 classes and 3 functions (1).
- My post explains global and nonlocal with 2 classes and 3 functions (2).
- My post explains global and nonlocal with 2 classes and 3 functions (3).
- My post explains global and nonlocal with 3 classes and 3 functions (1).
- My post explains global and nonlocal with 3 classes and 3 functions (2).
- My post explains global and nonlocal with 3 classes and 3 functions (3).
With 2 functions or generators, there are 3 kinds of variables from the viewpoint of second() as shown below:
*Memo:
- A global variable is the variable out of any functions and classes.
- A non-local variable is the variable within outer functions.
- A local variable is the variable which is within its function.
- A global and non-local variable can be accessed from a function or generator as long as the function or generator is called and run after them even if the function or generator is defined before them.
<Function>:
""" It's from the viewpoint of `second()` """ def first(): def second(): v = 4 # <- local variable print(v) # 4 return 3 v = second # <- Non-local variable print(v()) # 3 return 2 v = first # <- Global variable print(v()) # 2 <Generator>:
""" It's from the viewpoint of `second()` """ def first(): def second(): v = 4 # <- local variable print(v) # 4 yield 3 v = second() # <- Non-local variable print(next(v)) # 3 yield 2 v = first() # <- Global variable print(next(v)) # 2 A global statement can refer to a global variable as shown below:
*Memo:
- The doc explains the rules for local and global variables in Python.
<Function>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v print(v.__name__) # first v = second # <- ✖ v() print(v.__name__) # second v = first # <- 〇 v() print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v v.__name__ = 'Hello' print(v.__name__) # Hello v = second # <- ✖ v() print(v.__name__) # second v = first # <- 〇 v() print(v.__name__) # Hello <Generator>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v print(v.__name__) # first yield v = second() # <- ✖ next(v) print(v.__name__) # second yield v = first() # <- 〇 next(v) print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v v.__name__ = 'Hello' print(v.__name__) # Hello yield v = second() # <- ✖ next(v) print(v.__name__) # second yield v = first() # <- 〇 next(v) print(v.__name__) # Hello A nonlocal statement can refer to a non-local variable as shown below:
<Function>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v print(v.__name__) # second v = second # <- 〇 v() print(v.__name__) # second v = first # <- ✖ v() print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v v.__name__ = 'Hello' print(v.__name__) # Hello v = second # <- 〇 v() print(v.__name__) # Hello v = first # <- ✖ v() print(v.__name__) # first <Generator>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v print(v.__name__) # second yield v = second() # <- 〇 next(v) print(v.__name__) # second yield v = first() # <- ✖ next(v) print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v v.__name__ = 'Hello' print(v.__name__) # Hello yield v = second() # <- 〇 next(v) print(v.__name__) # Hello yield v = first() # <- ✖ next(v) print(v.__name__) # first Without a global or nonlocal statement, the closest non-local variable or a global variable can be referred to in order as shown below:
<Function>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): print(v.__name__) # second v = second # <- 〇 v() print(v.__name__) # second v = first # <- ✖ v() print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): v.__name__ = 'Hello' print(v.__name__) # Hello v = second # <- 〇 v() print(v.__name__) # Hello v = first # <- ✖ v() print(v.__name__) # first <Generator>:
Read:
""" It's from the viewpoint of `second()` """ def first(): def second(): print(v.__name__) # second yield v = second() # <- 〇 next(v) print(v.__name__) # second yield v = first() # <- ✖ next(v) print(v.__name__) # first Change:
""" It's from the viewpoint of `second()` """ def first(): def second(): v.__name__ = 'Hello' print(v.__name__) # Hello yield v = second() # <- 〇 next(v) print(v.__name__) # Hello yield v = first() # <- ✖ next(v) print(v.__name__) # first Using both a global and nonlocal statement in the same function or generator gets error as shown below:
<Function>:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v # SyntaxError: name 'v' is nonlocal and global nonlocal v print(v.__name__) v = second # <- ✖ v() print(v.__name__) v = first # <- ✖ v() print(v.__name__) """ It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v # SyntaxError: name 'v' is nonlocal and global global v print(v.__name__) v = second # <- ✖ v() print(v.__name__) v = first # <- ✖ v() print(v.__name__) <Generator>:
""" It's from the viewpoint of `second()` """ def first(): def second(): global v # SyntaxError: name 'v' is nonlocal and global nonlocal v print(v.__name__) yield v = second() # <- ✖ next(v) print(v.__name__) yield v = first() # <- ✖ next(v) print(v.__name__) """ It's from the viewpoint of `second()` """ def first(): def second(): nonlocal v # SyntaxError: name 'v' is nonlocal and global global v print(v.__name__) yield v = second() # <- ✖ next(v) print(v.__name__) yield v = first() # <- ✖ next(v) print(v.__name__) 
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