Templated SourceHook

[Mooshua]

Introduces one massive template for generating SourceHook managers. The goal is for this to simplify the definition of SourceHooks long-term by replacing macros with templates.

Draft until API is settled upon, but is most likely merge-able now.

Introducing SourceHook::HookImpl

SourceHook::HookImpl is a template that implements the previous functionality of the SH_DECL macros. It uses the following template parameters in it's implementation:

• ISourceHook** SH - Pointer to SourceHook (eg &g_SHPtr)
• Plugin* PL - Pointer to global PluginId value (eg &g_PLID)
• typename Interface - The interface to hook
• Result (Interface::Method)(Args...) - The argument to hook (eg &IEngine::DoThing
• typename Result - the return type or void
• typename ...Args - all arguments, specified as a varardic type pack.

The macro PLUGIN_GLOBALVARS() now exposes the Hook template with the SH and PL fields filled in from the global variables--so all plugin authors need to do to get started is specify `Hook<Interface, Method, Return, Args...>::Make().

Example usage:

//  Declares Hook<> template
PLUGIN_GLOBALVARS()

//                                 Interface       Method                     Result
//  Generic Hook                   vvvvv           vvvvv                      vvvv
auto OnGameInit = SourceHook::Hook<IServerGameDLL, &IServerGameDLL::GameInit, bool>::Make();
auto OnLevelInit = SourceHook::Hook<IServerGameDLL, &IServerGameDLL::LevelInit, bool, const char*, const char*, const char*, const char*, bool, bool>::Make();

//  Varfmt hook
//  virtual void ClientCommand(edict_t* pClient, const char* fmt, ...);
auto OnClientCommand = SourceHook::FmtHook<IVEngineServer, &IVEngineServer::ClientCommand, void, edict_t*>::Make();

void AddHooks()
{
	OnGameInit->Add(server, false, SH_MEMBER(this, &SourceProvider::Hook_GameInit));
 
        //  Alternative hook modes available in fourth argument (defaulting to Normal)
	OnLevelInit->Add(server, false, SH_MEMBER(this, &SourceProvider::Hook_LevelInit), ISourceHook::AddHookMode::Hook_VP);
}

[GAMMACASE]

Very neat stuff, but would throw my 2 cents here, what do you think on renaming exposed struct Hook to something more verbose, like SH_Hook? Just to prevent any potential name collisions and further confusion due to it on the user end.

[Mooshua]

Very neat stuff, but would throw my 2 cents here, what do you think on renaming exposed struct Hook to something more verbose, like SH_Hook? Just to prevent any potential name collisions and further confusion due to it on the user end.

How about "HookFactory" or "SourceHookFactory", since that's effectively what it is?

[dvander]

Thanks for doing this! Will take a look this weekend hopefully.

Namespaces are good avoiding for name collisions.

[Mooshua]

Added varardic hook macros, and I decided to just put the helpers into the SourceHook namespace. Hopefully this doesn't cause issues with plugins.

Split the original Hook template into four new templates: One for SourceHook -> Delegate APIs (HookHandlerImpl), one for Plugin -> SourceHook APIs (HookCoreImpl, and two handling the ABI for the raw hooks (HookImpl and FmtHookImpl). They're still a little rough around the edges and need some boundary refinement.

As a result of this, varfmt hooks are now supported, with similar handling to macro varfmt hooks:

auto OnClientCommand = SourceHook::FmtHook<IVEngineServer, &IVEngineServer::ClientCommand, void, edict_t*>::Make();

void SamplePlugin::Hook_SendClientCommand(edict_t* pEntity, const char* pszCommand)
{
    // pszCommand = printf(fmt, ...)
}

Still thinking about how I want to tackle manual hooks; open to suggestions.

[dvander]

Not everything has to be solved in one PR! Happy to take incremental improvements. API changes don't get frozen until release.

[Mooshua]

~~Don’t merge just yet—-just found some issues with reference return handling. Should be a quick fix.~~ FIXED.

On another note, are the test cases still maintained and regularly built? I’m getting some errors in the macros on MSVC and on GCC all of the tests fail. I was able to get it to build on windows by gutting some of the tests and all the tests passed there. Linux was WSL Debian x64 with G++ multilib (-m32)

[dvander]

There's also a build error:

/home/runner/work/metamod-source/metamod-source/metamod-source/core/sourcehook/sourcehook.h:1279:5: error: use of undeclared identifier 'vsnprintf'
                                vsnprintf(buf, sizeof(buf), fmt, ap);

I'm not sure why this didn't get pulled in as part of <cstdarg>.

[Mooshua]

I'm not sure why this didn't get pulled in as part of <cstdarg>.

Fixed. Hopefully. I think. Did a lot of the changes requested here! Working on tests & sample MM sometime in the future. Let me know if there's anything else that suits your fancy :^)

[MSWS]

LGTM!