Creating Interfaces

showdax · **Author**

I'm trying to create an interface in one plugin that can be used in other plugins. I'm not entirely sure how I expose the interface through sourcemm, and I'm having some issues just compiling my plugin with the new abstract class.

Code:

In file included from CServerPluginAccess.cpp:15:
CPlayerAccess.h: At global scope:
CPlayerAccess.h:73: error: invalid covariant return type for `virtual CUtlVector<CPlayerAccess*, CUtlMemory<CPlayerAccess*> >* CPlayerAccessManager::getPlayers() const'
IPlayerAccess.h:47: error:   overriding `virtual CUtlVector<IPlayerAccess*, CUtlMemory<IPlayerAccess*> >* IPlayerAccessManager::getPlayers() const'
CServerPluginAccess.cpp: In member function `virtual bool CServerPluginAccess::Load(PluginId, ISmmAPI*, factories*, char*, size_t)':
CServerPluginAccess.cpp:244: error: cannot allocate an object of type `CPlayerAccessManager'
CServerPluginAccess.cpp:244: error:   because the following virtual functions are abstract:
IPlayerAccess.h:48: error:  virtual void IPlayerAccessManager::getPlayersByIsValidated(CUtlVector<IPlayerAccess*, CUtlMemory<IPlayerAccess*> >*, bool) const
IPlayerAccess.h:49: error:  virtual void IPlayerAccessManager::getPlayersByAccess(CUtlVector<IPlayerAccess*, CUtlMemory<IPlayerAccess*> >*, byte) const
IPlayerAccess.h:50: error:  virtual void IPlayerAccessManager::getPlayersByLowestAccess(CUtlVector<IPlayerAccess*, CUtlMemory<IPlayerAccess*> >*) const

Here are the relevant definitions from the header files:

CPlayerAccess.h:

Code:

CUtlVector<CPlayerAccess *> *getPlayers() const;
void getPlayersByIsValidated(CUtlVector<CPlayerAccess *> *results, bool isValidated) const;
void getPlayersByAccess(CUtlVector<CPlayerAccess *> *results, byte access) const;
void getPlayersByLowestAccess(CUtlVector<CPlayerAccess *> *results) const;

IPlayerAccess.h:

Code:

virtual CUtlVector<IPlayerAccess *> *getPlayers() const = 0;
virtual void getPlayersByIsValidated(CUtlVector<IPlayerAccess *> *results, bool isValidated) const = 0;
virtual void getPlayersByAccess(CUtlVector<IPlayerAccess *> *results, byte access) const = 0;
virtual void getPlayersByLowestAccess(CUtlVector<IPlayerAccess *> *results) const = 0;

I haven't messed with creating my own interfaces before, so this is all pretty new to me.

BAILOPAN · 09-30-2005 , 12:29

First off you might need to swap const and =0 but I'm not sure.

I think the problem is that you are mixing and matching prototypes. The interface says you'll be returning things of IPlayerAccess, but your implementation is returning containers of CPlayerAccess.

showdax · 09-30-2005 , 15:05

I'm using covariant return types, and apparently I can't do that with parameters, but there's no way for me to get around the template parameter. CPlayerAccess inherits from IPlayerAccess, which is why I'm doing that.

Also, even when I do get this compiled, what do I do to expose the interface? And how do other plugins find the interface?

showdax · 09-30-2005 , 17:24

Okay well I got it compiled. For now I just made the functions in the implementation use vectors with IPlayerAccess objects, and have things static_cast them to CPlayerAccess when necessary. Now I just need to know how to expose the interface.

Edit: I'm using the SDK's interface exporting macros now, but I don't know how to get the CreateInterfaceFn for the plugin.

showdax · 10-01-2005 , 06:28

I've got it working now, but if anyone's curious about what I'm using, here's some code:

In the interface's header:

Code:

#define INTERFACEVERSION_MYINTERFACE "MyInterface001"

In the implementation's cpp file:

Code:

EXPOSE_SINGLE_INTERFACE_GLOBALVAR(CMyImplementation, IMyInterface, INTERFACEVERSION_MYINTERFACE, g_MySingleton);

In the plugin's cpp file (g_MySingleton is externed from the implementation's object file):

Code:

void *CreateInterfaceHook(const char *pName, int *pReturnCode)
{
	if (Q_strcmp(pName, INTERFACEVERSION_MYINTERFACE) == 0)
	{
		if (pReturnCode != NULL)
			* pReturnCode = IFACE_OK;

		FACTORY_RETURN(MRES_SUPERCEDE, (void *) g_MySingleton);
	}

	FACTORY_RETURN(MRES_IGNORED, NULL);
}

And then in my plugin's Load() function:

Code:

list->server = CreateInterfaceHook;

Then I tested it in AllPluginsLoaded():

Code:

IMyInterface *g_MyInterface = (IMyInterface *)((g_Ismm->serverFactory())(INTERFACEVERSION_MYINTERFACE, NULL))
if (g_MyInterface == NULL)
{
	META_CONPRINTF("WARNING! Could not find interface %s\n", INTERFACE_MINTERFACE);
}

sslice · 11-27-2005 , 14:43

How would you use SourceMM to expose an interface rather than the SDKs method?

BAILOPAN · 11-28-2005 , 10:47

You would override an input with your desired output in OnMetamodQuery in IMetamodListener.

Plugins can retrieve other plugin interfaces through g_SMAPI->MetamodQuery

(I think this is right, I don't have the code on me). I'll be updating the example plugin with the next release (which is sooner than you think, it's just a template library update and minor crash fixes).

sslice · 11-28-2005 , 16:13

Ahhh.. thanks, BAILOPAN.