Python’s handling of default parameter values is one of a few things that tends to trip up most new Python programmers (but usually only once). What causes the confusion is the behaviour you get when you use a “mutable” object as a default value; tha…

对于任何语言来说,函数都是一个重要的组成部分.在ES6以前,从JavaScript被创建以来,函数一直没有大的改动,留下了一堆的问题和很微妙的行为,导致在JavaScript中使用函数时很容易出现错误并且可能需要多余的代码实现一些基本的函数行为.在ES6中,函数有一个质的飞跃的改进,它充分考虑到过去数年间JavaScript开发者的需求和抱怨.与ES5相比,在ES6中使用函数开发不容易出错,而且更加灵活. 带默认参数的函数(Functions with Default Parameter Val…

Today an interesting bug (pitfall) is found when I was trying debug someone's code. There is a function which tries to check if an object exists or not. It has several parameters and some of them have default value. When using this function, the prog…

［python's default parameter］ 对于值类型(int.double)的default函数参数,函数不会保存对默认类型的修改.对于mutable objectd类型的默认参数,会有累积效应. 参考:http://docs.python.org/2.7/tutorial/controlflow.html…

欢迎关注我的新博客地址:http://cuipengfei.me/ 好久没有写博客了,上一次更新竟然是一月份. 说工作忙都是借口,咋有空看美剧呢. 这半年荒废掉博客说到底就是懒,惯性的懒惰.写博客这事儿,一丢掉就很久捡不起来. 闲话到此为止,下面进入正题. Default parameter value,默认参数值. 这个很容易理解,给参数一个默认值,如果调用者不显式指明参数值,则使用默认值.如果显式指明了,那就用显式指明的值. 举个例子: 1 def hello(name: String =…

我之前写了一篇关于Python参数传递(http://www.cnblogs.com/lxw0109/p/python_parameter_passing.html)的博客, 写完之后,我发现我在使用list的时候(我想在函数中改变实参),感觉使用文章中提到的传参理解还是有点儿迷惑和混乱 所以在此关于list的参数传递,再做一下补充和说明,这些是我个人的理解,如果您感觉有任何疑问或者不同的观点,非常 感谢您与我讨论,谢谢. #!/usr/bin/python #coding:utf-8 #Fil…

JavaScript函数的默认参数(default parameter) js函数参数的默认值都是undefined, ES5里,不支持直接在形参里写默认值.所以,要设置默认值,就要检测参数是否为undefined,按需求赋值. function multiply(a, b) { b = typeof b !== 'undefined' ? b : 1; return a*b; } multiply(5); // 5 multiply(5, 0); // 0 上面是MDN的相关例子,是比较严谨的…

When designing business classes, a common task is to ensure that a newly created business object is initialized with default property values. This topic explains how different types of properties can be initialized. As an example, a Contact business…

When designing business classes, a common task is to ensure that a newly created business object is initialized with default property values. This topic explains how different types of properties can be initialized. As an example, a Contact business…

I've recently been accumulating some MySQL configuration variables that have defaults which have proven to be problematic in a high-volume production environment. The thing they all have in common is a network blip or two can trigger some very undesi…