class | 易学教程

周记随笔4

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2019.12.18，天气晴，最近升温太厉害，感觉已经快到夏天了。。。目录讲点vue中的样式（1min）关于v-for（30s）讲点v-for喜欢出错的情况吧（3min）讲点vue中的样式（1min）在vue中，可以不用<div class="aaa bbb"></div> 用<div :class="['aaa','bbb']"></div> 比如： <style> .red { color: red; } .thin { font-weight: 200; } .italic { font-style: italic; } .active { letter-spacing: 0.5em; } </style> <body>  <h1 :class="['thin', 'italic']">这是一个很大很大的H1，大到你无法想象！！！</h1> </body> 当然也可以在:class中有三目运算符了  <h1 :class="['thin', 'italic', flag ? 'active' : '']">这是一个很大很大的H1，大到你无法想象！！！</h1> 如果flag为true就会使用.active样式

php mcrypt - decrypting and encrypting files?

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问题 I've been looking around for a php class that allows the decryption / encryption of pgp-encrypted csv files. Everything I've found has been primarily geared towards passwords. I'm assuming the principles are essentially the same, but was wondering if someone here can point me in the direction of a class specifically intended to receive files via FTP and decrypt them, as well as encrypt files and FTP them elsewhere? It's my first foray into encryption, so hoping that someone can point me to

Python. Strange class attributes behavior

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问题 >>> class Abcd: ... a = '' ... menu = ['a', 'b', 'c'] ... >>> a = Abcd() >>> b = Abcd() >>> a.a = 'a' >>> b.a = 'b' >>> a.a 'a' >>> b.a 'b' It's all correct and each object has own 'a', but... >>> a.menu.pop() 'c' >>> a.menu ['a', 'b'] >>> b.menu ['a', 'b'] How could this happen? And how to use list as class attribute? 回答1: This is because the way you're initializing the menu property is setting all of the instances to point to the same list, as opposed to different lists with the same value.

Python. Strange class attributes behavior

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How to load a jar from an URL without downloading it?

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问题 JAVA - Well just that, i know how to load external jars from my main project with classloader and even download a jar from an url and load it, but there's anyway to load a jar from a url without dowloading? just load it in memory from the url to use it? thanks! 来源： https://stackoverflow.com/questions/14751584/how-to-load-a-jar-from-an-url-without-downloading-it

Ruby Case class check

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问题 How can I get the following code to work (I want to decide upon an action based on the class of the arg): def div arg material = case arg.class when String [arg, arg.size] when Fixnum arg end material end 回答1: The comparison in the case statement is done with the === - also called the case equality operator. For classes like String or Fixnum it defined as to test if the object is an instance of that class. Therefore instead of a class just pass the instance to the comparison by removing the

Using structs of derived class y base template

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问题 I have a base template: template <typename T> class Base { public: void method(T); }; And a derived class: class Derived: public Base<Derived::status_t> { public: typedef struct { uint8_t value; } status_t; } I'm have more derived classes, each one with it status_t specific struct. I want to use these structs in the base class, but the compiler give me an error: Error[Pe070]: incomplete type is not allowed. I suppose that the problem is that the struct is not defined in the moment that the

Use Trait Function with Same Name but Optionally

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问题 PHP Class Using Same Name as Trait Function Refer to the question I just asked above here. Here was my original code. trait sampletrait{ function hello(){ echo "hello from trait"; } } class client{ use sampletrait; function hello(){ echo "hello from class"; //From within here, how do I call traits hello() function also? } } I can call the trait function like this thanks to the answer to the question. class client{ use sampletrait { hello as protected sampletrait_hello; } function hello(){

How to get an onCompletion handler from other class?

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问题 Another silly question from this Android newbie, please be patient with me... :) I've a class called Music that loads/plays music: public class Music implements OnCompletionListener{ MediaPlayer mediaPlayer; ... mediaPlayer.setOnCompletionListener(this); ... public void onCompletion(MediaPlayer mediaPlayer) { ... } ... } Then, I have another class called MainClass, with the UI, that loads a Music with Music track = Music(fileDescriptor); Now, what I want is to do something in the UI

Can I implement an interface in a C# in an .h file?

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问题 I have an interface that is used by several classes and the interface implementation is the same for all the classes. I would make it a base abstract class, but then it would stop the deriving classes from inhering from another class later on, which I need. So instead of reimplementing the same interface in all the classes, can I somehow implement the interface in one place, like an .h file and include the .h file in the cs file so the class "implements" the interface. By the way, the