overriding

问题 Is there a way to override the "undo" and "select all" in right click context menu of the browser over textarea? Thank you. 回答1: You cannot edit the browser's built-in context menu, but you can disable it and replace it with your own using the oncontextmenu event on the window object. I would caution that this is often a bad idea. Users expect to find the built-in context menu and are often frustrated when it isn't there. 回答2: I know you can prevent the whole context menu from opening by

问题 I'd like to know how to display an element contained within a parent element that has "display:none" characteristics. But leave the other children under that parent untouched. Here's a simple example: <div id="parent"> <p id="item1">Item should show</p> <p id="item2">Item should show</p> <p id="item3">Item should not show</p> <div><!--/parent--> <style> #parent {display: none;} #item3 {display: block !important;} </style> So in this example, I want #item3 to be displayed, but the rest of

问题 Hi i want to do the following. I simply want to overload the [] method in order to access the instance variables... I know, it doesn't make great sense at all, but i want to do this for some strange reason :P It will be something like this... class Wata attr_accessor :nombre, :edad def initialize(n,e) @nombre = n @edad = e end def [](iv) self.iv end end juan = Wata.new('juan',123) puts juan['nombre'] But this throw the following error: overload.rb:11:in `[]': undefined method 'iv' for #

问题 I use Apache Ivy for handling library dependency. In my company we have a "core" project which is released/versioned periodically. We then have many "customer" projects which are for a particular client. Each customer project uses a particular version of the core project which we maintain in the ivy.xml of the customer project. All fine. Sometimes someone will want to change core locally and test the change with a specific project. In that instance they will build the core and publish it to a

问题 I have read many questions on stackoverflow about polymorphism. The question is a question of structuring my ideas because I have read and researched a lot to the point where I have many ideas in mind. I need comments and criticism about my thoughts on polymorphism. I will use Java to demonstrate my ideas. Polymorphism is a characteristic of having different forms when talking about a certain entity. It could be achieved in the following ways: A derived class inherits from its base class all

问题 I have tried solutions, described in How to override an implicit value?, but it does not help. Here is a code example. A definition of TestImplicit abstraction with 2 different implementations (analogue of ExecutionContextExecutor ): trait TestImplicit { def f(s:String):Unit } object TestImplicitImpl1 extends TestImplicit { override def f(s: String): Unit = println(s"1: $s") } object TestImplicitImpl2 extends TestImplicit { override def f(s: String): Unit = println(s"2: $s") } And in the

问题 I am using scikit-learn and am building a pipeline. Once the pipeline is build, I am using GridSearchCV to find the optimal model. I am working with text data, so I am experimenting with different stemmers. I have created a class called Preprocessor that takes a stemmer and vectorizer class, then attempts to override the vectorizer's method build_analyzer to incorporate the given stemmer. However, I see that GridSearchCV's set_params just directly accesses instance variables -- i.e. it will

问题 I am attempting to install taps from my Heroku app folder. When I type "gem install taps," I get the following error: ERROR: While executing gem ... (Errno::EACCES) Permission denied - /Users/jacob/.rvm/gems/ruby-1.9.3-p194/gems/taps-0.3.24/bin/taps I attempted to remove the taps-0.3.24 folder using rm -r and got this question: override rwxr-xr-x root/staff for /Users/jacob/.rvm/gems/ruby-1.9.3-p194/gems/taps-0.3.24//bin/schema? Upon typing yes, it tells me permission denied. Here is the

问题 We have the following simple (and slightly modified to add main and output) example in the Standard: struct A { virtual void f() { cout << "A\n"; } }; struct B : virtual A { virtual void f() { cout << "B\n"; } }; struct C : B, virtual A { using A::f; }; int main() { C c; c.f(); // calls B​::​f, the final overrider c.C::f(); return 0; } From which we can make a conclusion that using A::f does not present an overrider. But what wording in the Standard dictates it? Here is the wording for the

问题 I use a library where an abstract class overrides a concrete method inherited from Object with an abstract method: public abstract class A { @Override public abstract boolean equals(Object obj); } To extend this class, I have to implement the equals method: public class B extends A { @Override public boolean equals(Object obj) { return obj != null && obj.getClass() == B.class; } } Why can an abstract method ( A::equals ) override a concrete method ( Object::equals )? I don't see the goal of