implementation

问题 This question already has answers here : Casting between two types derived from the (same) interface (9 answers) Casting between classes that share the same interface (7 answers) Casting a interface derived class to another derived class (1 answer) Closed 10 months ago . I have 2 classes which implement the same interface. But somehow I cannot cast them from one to another. Here's an example: public interface IObject { // ... } public class FooObject : IObject { // ... } public class

问题 I am a little with familiar with C++ and I know that for almost every header file, I must create source file to go with it. Now I am looking into java interfaces and implementation and it looks as the same thing. At first you just name the variables and methods in one class and then you define them in other class. Are these things in C++ and Java basically the same or similar? 回答1: Java interfaces and C++ header/implementation files are different concepts. C++ has a text compilation model. So

问题 I'm trying to figure it out what is the difference between api and implementation configuration while building my dependencies. In the documentation, it says that implementation has better build time, but, seeing this comment in a similar question I got to wonder if is it true. Since I'm no expert in gradle, I hope someone can help. I've read the documentation already but I was wondering about a easy-to-understand explanation. 回答1: Gradle compile keyword was deprecated in favor of the api and

问题 I've never encountered this issue before today and was wondering what convention/best practice for accomplish this kind of behavior would be. Basic setup is this: public interface IDispatch { void Dispatch(); } public class Foo : IDispatch { void IDispatch.Dispatch() { DoSomething(); } } public class Bar : Foo { ... } Bar needs to subclass Foo because it shares all the same properties as Bar plus introduces 2 new ones that I need to encounter for. The problem I have is that Foo also needs a

问题 I am planning on creating a Node Graph in pyqt. The abstract models that qt provides work for 1D, 2D and Tree data but the abstract class seems to break down for something like a node graph. In particular the "parent" function in QAbstractModel returns QModelIndex of a single parent. In a DAG I will may have multiple parents. One resource I found was this blog post: http://invalidmagic.wordpress.com/2009/12/10/qgraphicsscene-used-as-a-qabstractitemmodel/ It provides some useful information,

问题 I have written the following code in C++, however found out that I have to convert it in C. I am not C or even C++ programmer, please help. Can someone help me change this method to C directives, specifically vector implementation, following will not compile I have removed complexity to keep it simple. Thanks in anticipation. __declspec(dllexport) std::vector<MY_STRUCT> WINAPI ABC(char *strVal) { MY_STRUCT f; std::vector<MY_STRUCT> list = std::vector<MY_STRUCT>(); while (*dddd) { /*do the

问题 Due to the benchmarking done in other threads (cf. https://stackoverflow.com/a/397617/1408611) it was shown that instanceof in Java 6 is actually quite fast. How is this achieved? I know that for single inheritance, the fastest idea is having some nested interval encoding where each class maintains a [low,high] interval and an instanceof is simply an interval inclusion test, i.e. 2 integer comparisons. But how is it made for interfaces (as interval inclusion only works for single inheritance)

问题 Should be a newbie question... I have existing code in an existing class, A, that I want to extend in order to override an existing method, A::f(). So now I want to create class B to override f(), since I don't want to just change A::f() because other code depends on it. To do this, I need to change A::f() to a virtual method, I believe. My question is besides allowing a method to be dynamically invoked (to use B's implementation and not A's) are there any other implications to making a

问题 I was wondering if there was a way to implement semaphore in C++ (or C#), any libraries that'd help. I tried using OpenMP but I had no way of actually blocking threads, instead I had to busy wait on 'em which lead to deadlocks if/when I hadn't enough number of threads. So First I'm looking for a some library that would let me block/spawn/kill my threads. Secondly, are there any libraries out there that already implement semaphores? And finally, when I was introduced to the context of

问题 From the Linux manpage for memmove(3) The memmove() function copies n bytes from memory area src to memory area dest. The memory areas may overlap: copying takes place as though the bytes in src are first copied into a temporary array that does not overlap src or dest, and the bytes are then copied from the temporary array to dest. Instead of allocating a temporary array and copy the values twice we could just do the following: void *my_memmove(void *dest, const void *src, size_t n) { signed