2.关键字global,nonlocal

count=0

def func():

print(count)

count+=1

func()

UnboundLocalError: local variable 'count' referenced before assignment

解释器认为：如果你在局部作用域对一个变量进行修改了，

你在局部作用域已经定义好这个变量了。

global

1. 可以在局部作用域声明一个全局变量。

   这是剪切

   def func():
   	global name
   	name=1
   	print(globals())
   	# print(locals())
   	name+=1
   	print(globals())
   func()
   print(name)
   print(globals())
   '''
   {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x0000002B0802C160>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': ''__cached__': None, 'func': <function func at 0x0000002B07F71E18>, 'name': 1}
   {}
   {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x0000002B0802C160>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': '__cached__': None, 'func': <function func at 0x0000002B07F71E18>, 'name': 2}
   2
   {'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x0000002B0802C160>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': '__cached__': None, 'func': <function func at 0x0000002B07F71E18>, 'name': 2}
   '''
   

2. 可以修改全局变量。

   count=0
   def func():
   	global count
   	count +=1
   print(count)
   func()
   print(count)
   '''
   0
   1
   '''
   

nonlocal是复制

nonlocal 不能操作全局变量

nonlocal 可以对父级作用域的变量进行修改，并且在当前作用域创建（复制）一份此变量。

def func():
	count=0
	def inner():
		nonlocal count
		count +=1
		print(count)
		print(locals()){'count': 1}
	inner()
	print(locals())#{'inner': <function func.<locals>.inner at 0x00000088E186AAE8>, 'count': 1}
func()
'''
1
{'count': 1}
{'inner': <function func.<locals>.inner at 0x00000088E186AAE8>, 'count': 1}
'''
UnboundLocalError: local variable 'count' referenced before assignment
解释器认为：如果你在局部作用域对一个变量进行修改了，
你在局部作用域已经定义好这个变量了。