overriding

问题 I would like to create the following trait: trait IntSet[A] extends Traversable[A] { self: Product => def foreach[U](f: A => U): Unit } case class AProduct(a: List[Int], b: List[Int]) extends IntSet[Int] { def foreach[U](f: Int => U): Unit = { for(aa <- a; bb <- b) f(aa*bb) } } AProduct(List(1, 5,6,7), List(2,3,4,5)).toString returns (2, 3, 4, 5, 10, 15, 20, 25, 12, 18, 24, 30, 14, 21, 28, 35) But I don't want the toString method from the case class to be overriden by the one of the

问题 In order to better manage how I was making my database calls using Doctrine, I investigated how I could add the php debug_backtrace to the symfony doctrine db collector . I managed to identify the modifications I had to make but I did not yet found a good way to override the DebugStack class (apart from overriding the vendor class). the class is located here : vendor/doctrine/dbal/lib/Doctrine/DBAL/Logging/DebugStack.php For those who are interested, here is the result : To do this, you need

问题 I have same class in main application and a gem (mountable engine). I want to reopen the class(defined in main applicaion) in the gem. Main application has app/models/test.rb class Test def original_method end end in Gemfile gem 'gem_name' In the gem app/models/test.rb class Test def add_method end end But main application raises an error that Test#original_method is not defined. It looks like Test class is overwritten in the gem. Why not reopen? How can I solve the problem?? EDIT

问题 I am developing a simple project. And I have a conflict with meaning of Liskov Principle in my project. I simplified my question of my project with this example: public class Animal { public void feed() { // do something here } } public class Dog extends Animal { // some methods and attributes @Override public void feed() { // never call parent feed() method (super.feed()) } } So, my question is, if I don't call parent method and write a completely new codes in override method, Is this

问题 I'm trying to create an application on Symfony2 with Doctrine 2 entities. My problem is that I should have a main application which contains the mainly used functions and other applications which are gonna extend it on need. For example i have a UserInterface and also a User which implements UserInterface in the main App. All the other applications should be able to use this User, but in case one of the apps needs to add more properties to this User he is able to override the user class

问题 I'm faced with an annoying primefaces-bug. I have 2 commandLinks for changing languages: <p:commandLink action="#{language.setLanguage('de')}" ajax="false"> <h:graphicImage value="/resources/images/flags/germany.png" style="vertical-align: middle;width:40px;height:34px" /> </p:commandLink> if I change the locale now, the page is reloaded but it seems like the primefaces overrides are gone. At least the texts are bigger... Is this a familliar issue? regards 回答1: I would have just commented,

问题 I have a template that includes another template. This included template has block tags in it. Example: base.html BASE {% block title %}Base Title{% endblock %} {% block content %}{% endblock %} template1.html {% extends 'base.html' %} {% block title %}Extended Title{% endblock %} {% block content %} Extended content {% include 'include.html' %} {% endblock %} include.html {% block title %}Include Title{% endblock %} {% block another_content %}Include Content{% endblock %} What I'm expecting

问题 I have a hierarchy of classes: class C1 { virtual object M1(); } class C2: C1 { override sealed object M1(); } class C3: C2 { // I want to override M1() // CSC gives me an error, obviously override object M1(); } But it seems there is a way. In IL, you can override a method with a different name. So, we change the name ( M1_2() overrides M1() ), say it overrides the method on the base class ( C1::M1() ), a la explicit interface implementation, and the "final" on the intermediate ( C2 ) class

问题 I have problem understanding the below code(commented against the line number) class Base { void m1(Object o) { } void m2(String o) { } } public class Overloading extends Base { void m1(String s) { } void m2(Object o) { } public static void main(String[] args) { Object o = new Object(); Base base1 = new Base(); base1.m1("");//**why this works perfect** Base base = new Overloading(); base.m2(o);// **why compile time error** - The method m2(String) in the type Base is not applicable for the

问题 I'm struggling with the problem that the .onWindowFocusChanged() doesn't get called in my custom Activity class. My setup: Two tabs (containing Activity_1 and Activity_2) in a TabHost, where the 2nd tab is selected by default: tabHost.setCurrentTab(currentTabIndex); In both Activities, I added the onWindowFocusChanged() override (because I need to preform calculations after the layout is done drawing): @Override public void onWindowFocusChanged(boolean hasFocus) { super.onWindowFocusChanged