No matching overload found

[Phlox Icon]

I can't understand why luabind is giving me this error. I have a function bound with:

luabind::module( GetLua() ) [

luabind::class_<CGlobalEntityList>( "CGlobalEntityList" )  

.def( "FindEntityByName", ( CBaseEntity *( CGlobalEntityList::* )( CBaseEntity *, const char *, CBaseEntity *, CBaseEntity *, CBaseEntity *, IEntityFindFilter * )) &CGlobalEntityList::FindEntityByName )

];

to the function:

// uses default arguments

CBaseEntity *CGlobalEntityList::FindEntityByName( CBaseEntity *pStartEntity, const char *szName, CBaseEntity *pSearchingEntity, CBaseEntity *pActivator, CBaseEntity *pCaller, IEntityFindFilter *pFilter )

I have a CGlobalEntityList object called gEntList. I set NULL = 0 at the top of the file and made sure that it does equal 0. When I call the bound function using with the code:

gEntList:FindEntityByName( NULL, szName, NULL, NULL, NULL, NULL )

When I run the code, I get the following error:

[Lua-ERR] No matching overload found, candidates:

CBaseEntity* FindEntityByName(CGlobalEntityList&,CBaseEntity*,char const*,CBaseEntity*,CBaseEntity*,CBaseEntity*,IEntityFindFilter*)

This is really confusing because the first parameter in the message's function is CGlobalEntityList&. This was not what I defined with LuaBind earlier and no such function exists to match this definition. Is my binding code wrong somewhere? Thanks in advance.

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[James Porter-2]

Phlox Icon wrote:
> gEntList:FindEntityByName( NULL, szName, NULL, NULL, NULL, NULL )

Pointers don't exist in Lua (at least not the way you're doing it), and
this wouldn't work in C++ either (try defining "int null = 0;" and
passing that to your method - it'll fail). It would work if you bound
NULL to be a CBaseEntity* via Luabind.

> This is really confusing because the first parameter in the message's
> function is CGlobalEntityList&. This was not what I defined with LuaBind
> earlier and no such function exists to match this definition. Is my
> binding code wrong somewhere? Thanks in advance.

You may want to look into C++ calling conventions, since at the
implementation level, most compilers will pass an object as the first
parameter to its class's methods.

- Jim


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[Phlox Icon]

Thank you for your response, James. I did what you said and it worked immediately. I'll just paste the code here for Googlers in future:

//C++

//Global scope

CBaseEntity *NULL_CBaseEntity = NULL;

//in a function somewhere else

luabind::globals( GetLuaHandle()->GetLua() )["NULL_CBaseEntity"] = NULL_CBaseEntity;

-- in the Lua function

if( pStartEntity and szName ) then

if ( pStartEntity == NULL ) then

pStartEntity = NULL_CBaseEntity

end

-- call function

gEntList:FindEntityByName( pStartEntity, szName, NULL_CBaseEntity, NULL_CBaseEntity, NULL_CBaseEntity, NULL_CBaseEntity )

end

Sorry, but I have just one more question regarding this piece of code. This function returns a base class type. I'm wondering how to cast this another type. The Lua reference manual and PIL don't seem to mention casting of this type and Google hasn't been helpful. I basically want:

// in C++

DerivedType d = (DerivedType)g.getObject('objectName') ; // returned base object is cast to derived type

... // perform derivedType specific functions

but code to the same effect in Lua. Is there an easy LuaBind way of doing this? I've been at this for over a day so I'd also gladly settle for any way of doing this casting in Lua.

All input is appreciated :)

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