python 延迟绑定（late binding）

#!/usr/bin/env python3# -*- coding: utf-8 -*-' a test module '__author__ = 'Zhang Shuai'def operator():    return [lambda n: n * m for m in range(6)]print([o(3) for o in operator()])# 这是由于闭包函数引用的外部作用域的自由变量, 只有在内部函数被调用的时候才会搜索变量m的值, 由于循环已结束, m指向最终值5, 所以各函数调用都得到了相同的结果。# 即：def operator():   return [lambda m: 5 * n,lambda m: 5 * n,lambda m: 5 * n,lambda m: 5 * n,lambda m: 5 * n,lambda m: 5 * n]# 等价于def operator2():    l = []    for i in range(6):        def func(m):            return m * i        l.append(func)    return lprint([o(3) for o in operator2()])# 改进def operator3():    return [lambda n, m=m: n * m for m in range(6)]print([o(3) for o in operator3()])# 这就相当于给每个函数一个默认参数# 即：# def operator3():#     return [lambda n, m=0: m * n, lambda n, m=1: m * n, lambda n, m=2: m * n, lambda n, m=3: m * n,#             lambda n, m=4: m * n, lambda n, m=5: m * n]def operator4():    l = []    for i in range(6):        def func(m, i=i):            return m * i        l.append(func)    return lprint([o(3) for o in operator4()])