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Trying to register a function that returns a asIScriptObject


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#1 Isaac Paul   Members   -  Reputation: 189

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Posted 23 January 2013 - 07:32 AM

I have a function like this:

 

asIScriptObject* ComponentScripted::getProperty(const std::string &key) const 

 

and I'm registering it like this:

 

r = engine->RegisterObjectMethod(strComponent, "?& get(const string &in) const", asMETHODPR(ComponentScripted,getProperty,(const std::string&) const,asIScriptObject*), asCALL_THISCALL); assert( r >= 0 );

 


However, it doesn't seem like ?& is a valid return type. How would I return a asIScriptObject back to the script from c++?

 

Any help would be greatly appreciated. Thank you.


Edited by izackp, 23 January 2013 - 07:33 AM.


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#2 Andreas Jonsson   Moderators   -  Reputation: 3451

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Posted 23 January 2013 - 07:48 AM

?& cannot be used for return values.

 

If the script classes have a common interface that is known by the application then you can do it like this:

 

engine->RegisterInterface("MyIntf");
engine->RegisterObjectMethod(strComponent, "MyIntf &get(const string &in) const", asMETHODPR(ComponentScripted, getProperty, (const std::string &) const, asIScriptObject *), asCALL_THISCALL);

 

If the script classes doesn't have anything in common you can use a wrapper class that returns a CScriptHandle with the reference to the script class. See the add-on for info on how to use the CScriptHandle.

 

Regards,

Andreas


AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

#3 Isaac Paul   Members   -  Reputation: 189

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Posted 29 January 2013 - 11:02 PM

Thanks the interface method worked pretty cleanly.  I still need a little help, so maybe you can just point me in the right direction. I was trying to create a script object in c++ of a class declared in angelscript with this code:

    asIScriptModule* mod = builder.GetModule();
    int logicTypeId = mod->GetTypeIdByDecl("LogicComponent");
    asIScriptObject* objLogicComp = static_cast<asIScriptObject *>(engine->CreateScriptObject(logicTypeId));
    assert(objLogicComp != NULL);

 

 

and I get this error when calling CreateScriptObject:


(0, 0) : ERR  : Failed in call to function 'Prepare' with 'null' (Code: -6)

 

which leads me to believe that I cant do this either or I'm missing a step that allows me to do this. I verified that the name of the class is the same as the parameter for gettypeidbydecl.. so I'm not sure what the problem is


Edited by izackp, 29 January 2013 - 11:04 PM.


#4 Andreas Jonsson   Moderators   -  Reputation: 3451

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Posted 30 January 2013 - 07:39 AM

Ah, this must be because the script class that you're trying to create doesn't have a default constructor. I see that I'm missing a validation for this case in AngelScript and the code ends up trying to execute the non-existent constructor, thus you see the error: 'Prepare' with 'null'. I'll have this fixed to add a proper validation for this case.

 

However, as the script object doesn't have a default constructor you cannot use the CreateScriptObject() method to create it. Instead you'll have to manually call one of the non-default constructors with the appropriate arguments.

 

// Find the correct factory function
asIScriptModule *mod = builder.GetModule();
asIObjectType *type = mod->GetObjectTypeByName("LogicComponent");
asIScriptFunction *func = type->GetFactoryByDecl("LogicComponent @LogicComponent(int)");
 
// Call the factory function to create the object
asIScriptContext *ctx = engine->CreateContext();
ctx->Prepare(func);
ctx->SetArgDWord(0, 42);
ctx->Execute();
 
// Store the object
asIScriptObject *obj = reinterpret_cast<asIScriptObject*>(ctx->GetReturnObject());
obj->AddRef();
 
// Clean up
ctx->Release();

 

Regards,

Andreas


AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

#5 Isaac Paul   Members   -  Reputation: 189

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Posted 30 January 2013 - 08:16 AM

Wow thanks, I would of never have figured that out.. at least quickly..

 

Thanks for your help.



#6 Isaac Paul   Members   -  Reputation: 189

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Posted 31 January 2013 - 12:46 PM

Hmm it seems I've run into something again. I have a factory function for my LogicComponentScripted (c++ version of LogicComponent)

static void LCSFactoryArgs(asIScriptGeneric *gen)
{
    void *parentComponent = gen->GetArgAddress(0);
    LogicComponentScripted *self = reinterpret_cast<LogicComponentScripted*>(gen->GetObject());
    assert(self != NULL);
    gen->SetReturnAddress(new LogicComponentScripted((asIScriptObject*)self, (Component*)parentComponent));
}
Registration Function:
r = engine->RegisterObjectBehaviour(type, asBEHAVE_FACTORY, "LogicComponentInner@ f(ComponentInner@& in)", asFUNCTION(LCSFactoryArgs), asCALL_GENERIC); assert( r >= 0 );

 

 

It seems if I call GetObject when I create a LogicComponentInner inside of a Scripted object's constructor it returns NULL. Which sort of makes sense since the script object isn't done constructing. Is it possible to get a reference to the scripted object when creating a c++ object in the constructor of the scripted class?

 

Overall, what im trying to do is have a parallel C++ object that has a reference to a Scripted object and vice-versa. 



#7 Andreas Jonsson   Moderators   -  Reputation: 3451

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Posted 31 January 2013 - 01:20 PM

You've misunderstood what the GetObject() is used for. This method returns the object upon which the class method is called. For global functions, such as the factory behaviour, GetObject() will always return null.

 

The pointer/handle to the script class should be passed as argument to the factory function. Then the script class' constructor can call the C++ object's factory function and pass itself as argument.


AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game

#8 Isaac Paul   Members   -  Reputation: 189

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Posted 31 January 2013 - 01:57 PM

ah thank you again.






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