C++, Abstract Factory and Strategy patterns?

Question

JavaScript

Are there ready-made libraries for implementing such code?

BaseHandler::registerType<InfoHandler>(1);<br>
BaseHandler::registerType<AuthHandler>(2);<br>
<br>
BaseHandler* handler = BaseHandler::factory(1); //Находим обработчик по ID<br>

This is an attempt to shorten this code:

BaseHandler* handler = 0;<br>
<br>
switch(type)<br>
{<br>
      case 1:<br>
            handler = new InfoHandler;<br>
            break;<br>
<br>
      case 2:<br>
            handler = new AuthHandler;<br>
            break;<br>
}

When there are 3-4 such handlers, then everything is fine. And for 20 I came up with only such a detour. To solve the problem, I wrote a template class, but the linker swears at it, and did not find why ... so I'm looking for ready-made libraries.

PS In C++, isn't it possible to take out the implementation of the template class implementation from the header file? (the linker swears at this)

Answer 1

I have not seen such ready-made libraries, but it is impossible to take the implementation beyond the headers for sure. A template class only generates a concrete class the first time it is used. As far as I remember, if you immediately implement a specific instance in the header, then you can move the code to a cpp file, but then the meaning of the templates is lost.