How does godot's NetSocket creates an instance?

Question

I'm reading the source code of godot, and I can't understand how NetSocket class creates its instance.

In net_socket.cpp, create() is defined, but I can't see how it works.

#include "net_socket.h"

NetSocket *(*NetSocket::_create)() = NULL;

NetSocket *NetSocket::create() {

    if (_create)
        return _create();

    ERR_PRINT("Unable to create network socket, platform not supported");
    return NULL;
}

Especially, what is _create? And what does NetSocket *(*NetSocket::_create)() = NULL; do actually?

Related: https://stackoverflow.com/questions/35654908/explanation-of-function-pointers - not exactly a duplicate, but it should get you started :) — Caramiriel, Jan 19 '19 at 13:13
Please show `_create()` - without it the question is not answerable. — Jesper Juhl, Jan 19 '19 at 13:17
_@42milez_ Check where in the source code the `NetSocket::_create` function pointer is set to a specific function. It sounds like there are several platform specific implementations for that function (most probably in classes derived from `NetSocket`). — πάντα ῥεῖ, Jan 19 '19 at 13:38

score 2 · Accepted Answer · answered Jan 19 '19 at 14:04

2

You're looking at the wrong file. That one just delegates to whatever platform-specific implementation has been linked in/instantiated, using a function pointer called _create.

It is set in, for example, the POSIX impl.

Simply search the codebase for instances of _create and you'll see how it works.

answered Jan 19 '19 at 14:04

Lightness Races in Orbit

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Thanks! I understand the implementation. – 42milez Jan 19 '19 at 14:32
@42milez Nice one. Further reading, maybe: https://isocpp.org/wiki/faq/pointers-to-members – Lightness Races in Orbit Jan 19 '19 at 14:32
I hadn't known pointer-to-member-function at all, but I got a new technique because of your help. Thank you :) – 42milez Jan 20 '19 at 01:25

How does godot's NetSocket creates an instance?

1 Answers1