In C# you can put a constraint on a generic method like: public class A { public static void <T> Method (T a) where T : new() { //...do something... } } Is there also a way to put a constraint like "there exists a constructor with a float[,] parameter?" The following code doesn't compile well: public class A { ...
For example, a class named Table, with its constructor being: Table(string name="", vector <string> mods); How would I initialize the vector to be empty? Edit: Forgot to mention this was C++. ...
Take this skeleton class that someone wants to fill in to fetch RSS streams on a series of web sites: public class RSSStream extends Thread { public RSSStream(String rssStreamName,String rssURL,int refreshTime){ // constructor code goes here } } Now, let's consider that refreshTime has to be higher than zero and that rss...
I feel like I'm missing something here; can someone point out what I'm misunderstanding?! I've got two classes, an Abstract and a Concrete, as follows: public abstract class Abstract { protected static int ORDER = 1; public static void main (String[] args) { Concrete c = new Concrete("Hello"); } public Abs...
Hi. I have been a Java programmer for a while and I am trying to switch to ruby for a while. I was just trying to develop a small test program in ruby and my intention is something like following. I want to create a simple linked list type of an object in ruby; where an instance variable in class points to another instance of same typ...
I have a LINQ-to-SQL class called Task. I also have a partial class called Task which adds methods to its functionality: public partial class Task : Item {... However, now I want to execute code when a Task object is constructed but if I had a constructor: public Task() { ... } it tells me: 'TestApp.Models.Task' already d...
Hi All, I'm learning c++ coming from a java background (knowing a little C from many years ago)... in Java, it's common practice to use "this" inside a constructor to distinguish the variable passed in as arguments to the constructor from the one declared in the class: class Blabla { private int a; private int b; Blabla(i...
In C#, when you do Class(Type param1, Type param2):base(param1) is the constructor of the class executed first, and then the superclass constructor is called or does it call the base constructor first? ...
If I save some object in a php session variable $_SESSION['geoip'] = new GeoIP(); and then on future page loads I use $geoip = $_SESSION['geoip'], will it call the constructor? My constructor for that GeoIP class is making a call to an remote API (CURL), so I was hoping to save on API calls by only doing it the first time and then stori...
Hi I have an aspect that writes something to the console on exception. I have a base class that throws an exception on its constructor, and a derived class that have the aspect on its constructor. I would expect that the derived class aspect on constructor will catch the base class exception, but it dont. Is this by design? Is this a ...
union members may not have destructors or constructors. So I can't template the following class Foo on my own MyClass if MyClass has a constructor: template<class T> struct Foo { T val; Foo(T val_) : val(val_) {} size_t hash() const { union {T f; size_t s;} u = { val }; return u.s; } }; struct MyClass { bool a; doubl...
Here is what I'd like to do: function a() { // ... } function b() { // Some magic, return a new object. } var c = b(); c instanceof b // -> true c instanceof a // -> true b instanceof a // -> true Is it possible? I can make b be an instance of a easily by hooking a into its prototype chain but then I have to do new b(), which is...
In Scala, how does one define a local parameter in the primary constructor of a class that is not a data member and that, for example, serves only to initialize a data member in the base class? For example, in the following code, how could I properly define parameter b in the primary constructor of class B so that it generates only a te...
Short of renaming the constructor parameter in the primary constructor of class B, what change can I make to the following code (without changing its function) so that Scala will compile it successfully? Example: class A(var a: Int) class B(a: Int) extends A(a) { def inc(value: Int) { this.a += value } } Error: $ scala construct.s...
Suppose you have a class Person : public class Person { public string Name { get; set;} public IEnumerable<Role> Roles {get; set;} } I should obviously instanciate the Roles in the constructor. Now, I used to do it with a List like this : public Person() { Roles = new List<Role>(); } But I discovered this static method i...
I'm working on a player inventory system for a game. I have a struct Slot which has a List<Loot> collection that represents which kinds of items are allowed in it. The abstract class Loot is subclassed by all items which are lootable - i.e.: would be valid Content values for the Slot struct. I want to express that a Slot can have res...
class A{ A(int a = 5){ DoSomething(); A(); } A(){...} } Can the first constructor call the second one? ...
Please see the code bellow: 01. class Test { 02. public function __construct($param1, $param2, $param3) { 03. echo $param1.$param2.$param3; 04. } 05. } 06. 07. $params = array('p1','p2','p3'); 08. 09. $ob = new Test; 10. 11. if(method_exists($ob,'__construct')) { 12. call_user_func_array(array($ob,'__construct'),$...
I have a templated class A<T, int> and two typedefs A<string, 20> and A<string, 30>. How do I override the constructor for A<string, 20> ? The following does not work: template <typename T, int M> class A; typedef A<std::string, 20> one_type; typedef A<std::string, 30> second_type; template <typename T, int M> class A { public: A(...
I've got a peculiar error writing some C++/CLI code. I'm trying to make a copy of a class which holds some data. The class is defined as: public ref class RawDataPacket { protected: float* m_internalData; public: RawDataPacket(const float* newInternalData); RawDataPacket(const RawDataPacket^ rdp); RawDataPacket(RawDataPacket^ rdp)...