overriding

Implement two functions with the same name but different, non-covariant return types due to multiple abstract base classes

由 六眼飞鱼酱① 提交于 2019-12-07 03:16:34
问题 If I have two abstract classes defining a pure virtual function with the same name, but different, non-covariant return types, how can I derive from these and define an implementation for both their functions? #include <iostream> class ITestA { public: virtual ~ITestA() {}; virtual float test() =0; }; class ITestB { public: virtual ~ITestB() {}; virtual bool test() =0; }; class C : public ITestA, public ITestB { public: /* Somehow implement ITestA::test and ITestB::test */ }; int main() {

Scala HashMap of Lists: simpler default?

由 陌路散爱 提交于 2019-12-07 03:13:16
问题 I need a HashMap of Lists. Normally I do this: val lists = mutable.HashMap[String,List[Int]]() { override def default(key: String) = { val newList = List[Int]() this(key) = newList newList } } so that I can then simply write things like lists("dog") ::= 14 without having to worry about whether the "dog" List has been initialised yet. Is there a cleaner way to do this? I find myself typing out those five default override lines again and again. Thanks! 回答1: What about withDefaultValue() ? val

Easy way of overriding default methods in custom Python classes?

由 和自甴很熟 提交于 2019-12-07 02:30:29
问题 I have a class called Cell: class Cell: def __init__(self, value, color, size): self._value = value self._color = color self._size = size # and other methods... Cell._value will store a string, integer, etc. (whatever I am using that object for). I want all default methods that would normally use the "value" of an object to use <Cell object>._value so that I can do: >>> c1 = Cell(7, "blue", (5,10)) >>> c2 = Cell(8, "red", (10, 12)) >>> print c1 + c2 15 >>> c3 = Cell(["ab", "cd"], "yellow",

Overriding operator new/delete in derived class

由 江枫思渺然 提交于 2019-12-07 02:18:10
问题 I have a stateless, abstract base class from which various concrete classes inherit. Some of these derived classes are stateless as well. Because many of them are created during a run, I'd like to save memory and overhead by having all stateless derived classes emulate a singleton, by overriding operator new()/delete(). A simplified example would look something like this: #include <memory> struct Base { virtual ~Base() {} protected: Base() {} // prevent concrete Base objects }; struct D1 :

Overriding generic function error in swift

由 笑着哭i 提交于 2019-12-07 02:02:36
问题 Here's the code: class Test<T> { func foo<S:SequenceType where S.Generator.Element == T>(par : S){ print("foo") } } class TestInh : Test<Int> { override func foo<S:SequenceType where S.Generator.Element == Int>(par : S) { print("loo") } } And it yells such error: repl.swift:8:19: error: method does not override any method from its superclass override func foo<S:SequenceType where S.Generator.Element == Int>(par : S) { ~~~~~~~~ ^ How could I override the method in super class Test<Int> ? =====

Can a virtual function be overridden by a non-virtual function?

由 倾然丶 夕夏残阳落幕 提交于 2019-12-07 01:54:19
问题 In this code: class Base { public: virtual void method() = 0; }; class Derived1 : public Base{ public: virtual void method() override { } }; class Derived2 : public Base{ public: void method() override { } }; Is there any difference between Derived1 and Derived2 ? 回答1: From section 10.3 Virtual functions of the c++11 standard (draft n3337) point 2: If a virtual member function vf is declared in a class Base and in a class Derived, derived directly or indirectly from Base, a member function vf

EclipseLink MOXy: Override rules of binding files

由 落爺英雄遲暮 提交于 2019-12-07 01:53:28
I would, in the scenario below, like the binding of java-type name="SubClass" to be applied to set the text field on SuperClass. However it is not. Is there a problem with overriding the bindingsA.xml? According to the Overriding rules documentation : If the same java-type occurs in multiple files, any values that are set in the later file, will override values from the previous file What do I need to do to make it work? Input: <?xml version="1.0" encoding="UTF-8"?> <a text="A text">B text</a> Bindings A: <?xml version="1.0"?> <xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds

How can I override .hgrc options on the command line?

由 ◇◆丶佛笑我妖孽 提交于 2019-12-07 01:52:26
问题 I typically want to ignore white space changes when diff'ing with mercurial. If I set this as a default by putting ignorews = true in my .hgrc's [diff] section then there doesn't seem to be a way to force the display of white space changes for a single invocation on the command line. What am I missing? FWIW: None of the relevant command line options accepts an argument. Using the (deprecated) [defaults] section has the same behavior. I'm assuming the final answer will be "use an alias for

Java overriding two interfaces, clash of method names

由 旧巷老猫 提交于 2019-12-07 01:07:39
问题 I am implementing the Map<V,K> and the Collection<V> interface in one class, but the remove(Object) method occurs in both interfaces, therfore eclipse shows me some errors. The return types are different, one returns boolean and the other V but that doesn't seem to matter. Is there some way of telling java/eclipse which method is actually being overridden? EDIT: I have got an interface that all values must implement, it supplies the value with a getKey() method, making it possible to write an

How to override a function in another javascript file?

由 被刻印的时光 ゝ 提交于 2019-12-06 23:10:11
问题 I have a JavaScript file, Mybasefile.js , which has the function Mybasefunction() . I want to override this function in another JavaScript file. When the function is called in a button click, I want the original Mybasefunction() to be executed along with some other code. How can I do this? 回答1: place this code in the override file. Make sure the override file is included after the orginal one. var orig_Mybasefunction = window.Mybasefunction; window.Mybasefunction = function(){ orig
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