Question

可能重复：
Short Description of Python Scoping Rules

我写了两个简单的函数：

# coding: utf-8
def test():
    var = 1 
    def print_var():
        print var 
    print_var()
    print var 

test()
# 1
# 1
def test1():
    var = 2 
    def print_var():
        print var 
        var = 3 
    print_var()
    print var 

test1()
# raise Exception

相比之下，test1()在print var之后分配值，然后引发异常：UnboundLocalError: local variable 'var' referenced before assignment，我认为当我调用内部print var时，var的值为2我错了吗？

Answer 1

是的，你在这里不正确。函数定义引入了一个新的范围。

# coding: utf-8
def test():
    var = 1 
    def print_var():
        print var    <--- var is not in local scope, the var from outer scope gets used
    print_var()
    print var 

test()
# 1
# 1
def test1():
    var = 2 
    def print_var():
        print var     <---- var is in local scope, but not defined yet, ouch
        var = 3 
    print_var()
    print var 

test1()
# raise Exception

怀疑python变量范围

1 个答案: