*Memo:
- 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 (3).
A nonlocal statement can refer to a non-local variable as shown below:
<Read(Intuitive version)>:
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
num = 4 # <- ✖
class Cls2:
num = 5 # <- ✖
def second(self):
num = 6 # <- 〇
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # Here
print(num) # 6
Cls3().third()
Cls2().second()
Cls1().first()
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
num = 4 # <- 〇
class Cls2:
num = 5 # <- ✖
def second(self):
# num = 6 # <- Commented
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # Here
print(num) # 4
Cls3().third()
Cls2().second()
Cls1().first()
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
# num = 4 # <- Commented
class Cls2:
num = 5 # <- ✖
def second(self):
# num = 6 # <- Commented
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # SyntaxError: no binding
print(num) # for nonlocal 'num' found
Cls3().third()
Cls2().second()
Cls1().first()
<Read(Unintuitive version)>:
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # Here
print(num) # 6
num = 7 # <- ✖
num = 6 # <- 〇
Cls3().third()
num = 5 # <- ✖
num = 4 # <- ✖
Cls2().second()
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # Here
print(num) # 4
num = 7 # <- ✖
# num = 6 # <- Commented
Cls3().third()
num = 5 # <- ✖
num = 4 # <- 〇
Cls2().second()
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # SyntaxError: no binding
print(num) # for nonlocal 'num' found
num = 7 # <- ✖
# num = 6 # <- Commented
Cls3().third()
num = 5 # <- ✖
# num = 4 # <- Commented
Cls2().second()
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
<Change(Intuitive version)>:
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
num = 4 # <- ✖
class Cls2:
num = 5 # <- ✖
def second(self):
num = 6 # <- 〇
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # Here
num += 10 # Here
print(num) # 16
Cls3().third()
print(num) # 16
Cls2().second()
Cls1().first()
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
num = 4 # <- 〇
class Cls2:
num = 5 # <- ✖
def second(self):
# num = 6 # <- Commented
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # Here
num += 10 # Here
print(num) # 14
Cls3().third()
Cls2().second()
print(num) # 14
Cls1().first()
""" It's from the viewpoint of `third()` """
num = 2 # <- ✖
class Cls1:
num = 3 # <- ✖
def first(self):
# num = 4 # <- Commented
class Cls2:
num = 5 # <- ✖
def second(self):
# num = 6 # <- Commented
class Cls3:
num = 7 # <- ✖
def third(self):
nonlocal num # SyntaxError: no binding
num += 10 # for nonlocal 'num' found
print(num)
Cls3().third()
Cls2().second()
print(num)
Cls1().first()
<Change(Unintuitive version)>:
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # Here
num += 10 # Here
print(num) # 16
num = 7 # <- ✖
num = 6 # <- 〇
Cls3().third()
print(num) # 16
num = 5 # <- ✖
num = 4 # <- ✖
Cls2().second()
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # Here
num += 10 # Here
print(num) # 14
num = 7 # <- ✖
# num = 6 # <- Commented
Cls3().third()
num = 5 # <- ✖
num = 4 # <- 〇
Cls2().second()
print(num) # 14
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
""" It's from the viewpoint of `third()` """
class Cls1:
def first(self):
class Cls2:
def second(self):
class Cls3:
def third(self):
nonlocal num # SyntaxError: no binding
num += 10 # for nonlocal 'num' found
print(num)
num = 7 # <- ✖
# num = 6 # <- Commented
Cls3().third()
num = 5 # <- ✖
# num = 4 # <- Commented
Cls2().second()
print(num)
num = 3 # <- ✖
num = 2 # <- ✖
Cls1().first()
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