Python 关于Python函数参数传递方式的一点探索

关于Python函数参数传递方式的一点探索

by:授客 QQ：1033553122

实践代码

#!/usr/bin/env python

# -*- coding:utf-8 -*-

__author__ = 'laifuyu'

 

 

def function1(int_obj, float_obj, str_obj, boolean_obj, list_obj, tuple_obj, set_obj, dict_obj):

    print(' value of args of function1: ')

    print('int_obj:  %s id:%s' % (int_obj, id(int_obj)))

    print('float_obj:  %s id:%s' % (float_obj, id(float_obj)))

    print('str_obj:  %s id:%s' % (str_obj, id(str_obj)))

    print('boolean_obj:  %s id:%s' % (boolean_obj, id(boolean_obj)))

    print('list_obj:  %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj:  ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj:  %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj:  %s id: %s' % (dict_obj, id(dict_obj)))

 

    int_obj = 8

    float_obj = 9.0

    str_obj = 'ishouke'

    boolean_obj = True

    list_obj = ['i', 'shou', 'ke']

    tuple_obj = ('shou', 'ke', '2014')

    set_obj = {'shouke', '2014'}

    dict_obj = {'time':2014, 'author':'shouke'}

 

    print(' value of obj after value changed in function1: ')

    print('int_obj:  %s id:%s' % (int_obj, id(int_obj)))

    print('float_obj:  %s id:%s' % (float_obj, id(float_obj)))

    print('str_obj:  %s id:%s' % (str_obj, id(str_obj)))

    print('boolean_obj:  %s id:%s' % (boolean_obj, id(boolean_obj)))

    print('list_obj:  %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj:  ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj:  %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj:  %s id: %s' % (dict_obj, id(dict_obj)))

 

def function2(list_obj, tuple_obj, set_obj, dic_obj):

    list_obj[2] = '2014'

    tuple_obj[2][0] = '2016'

    set_obj.add('2014')

    dict_obj['time'] = 2014

 

    print(' value of obj after value changed in function2: ')

    print('list_obj:  %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj:  ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj:  %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj:  %s id: %s' % (dict_obj, id(dict_obj)))

 

 

if __name__ == '__main__':

    int_obj = 6

    float_obj = 7.0

    str_obj = 'shouke'

    boolean_obj = False

    list_obj = ['shou', 'ke', 'python']

    tuple_obj = ('shou', 'ke', ['2014'])

    set_obj = {'i', 'shouke'}

    dict_obj = {'time':2016, 'author':'ishouke'}

 

    print('value of obj in main before function1 called: ')

    print('int_obj:  %s id:%s' % (int_obj, id(int_obj)))

    print('float_obj:  %s id:%s' % (float_obj, id(float_obj)))

    print('str_obj:  %s id:%s' % (str_obj, id(str_obj)))

    print('boolean_obj:  %s id:%s' % (boolean_obj, id(boolean_obj)))

    print('list_obj:  %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj:  ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj:  %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj:  %s id: %s' % (dict_obj, id(dict_obj)))

 

    function1(int_obj, float_obj, str_obj, boolean_obj, list_obj, tuple_obj, set_obj, dict_obj)

 

    print(' value of obj in main after function1 called: ')

    print('int_obj: %s id:%s' % (int_obj, id(int_obj)))

    print('float_obj: %s id:%s' % (float_obj, id(float_obj)))

    print('str_obj: %s id:%s' % (str_obj, id(str_obj)))

    print('boolean_obj: %s id:%s' % (boolean_obj, id(boolean_obj)))

    print('list_obj: %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj: ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj: %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj: %s id: %s' % (dict_obj, id(dict_obj)))

 

    function2(list_obj, tuple_obj, set_obj, dict_obj)

    print(' value of obj in main after function2 called: ')

    print('list_obj: %s id:%s' % (list_obj, id(list_obj)))

    print('tuple_obj: ',tuple_obj, ' id: ', id(tuple_obj))

    print('set_obj: %s id: %s' % (set_obj, id(set_obj)))

    print('dict_obj: %s id: %s' % (dict_obj, id(dict_obj)))

 

 

输出结果

  

说明：比较main中，function1中接收的对象参数的值，id，不难发现：python中参数传递都是按“引用”传递，而非按“值”传递。

 

说明：对比，main，function1中参数对象被修改前，修改后的值，id，不难发现：当执行 var_name = value 语句时，实际把一个新的对象，赋值给左侧的var_name变量，，赋值后 id(var_name) = id(value),,更加有力的说明python中一切皆对象。

 

说明：对比main，function2中参数对象被修改前，修改后的值，不难发现：当仅修改可变对象的组成项的值时，而不是直接对整个对象赋值的情况下，修改的是本对象自身。