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AnantaDas

AngelScript "this"?

4 posts in this topic

Hello, I've got a question about AngelScript. I need to pass a reference to a script class instance into C++ for future access, so I created a function and exported it to AScript using "void InitScriptInstance( ?&in )". It works fine but the problem is I don't know how to pass a reference to current object (like 'this' in C++) - when I try to write:

 

class MyClass
{
   MyClass()
   {
      InitScriptInstance( this );
   }
}

 

The program goes into an infinite loop. If I replace the 'this' with something else (like 5) it works well but this obviously isn't what I need. Anyone knows the correct syntax?

 

Thanks

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The problem is that with &in the reference is not to the actual object. Instead the reference is to a copy of the object, in order to guarantee that the original is not modified. As the copy is performed within the constructor the infinite loop occurs.

You should pass a reference to a handle instead, i.e. InitScriptInstance(@this);

This will pass a reference to a handle to the object. Observe that your c++ function will need to dereference the reference in order to get the actual object.

Regards,
Andreas
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The problem is that with &in the reference is not to the actual object. Instead the reference is to a copy of the object, in order to guarantee that the original is not modified. As the copy is performed within the constructor the infinite loop occurs.

You should pass a reference to a handle instead, i.e. InitScriptInstance(@this);

This will pass a reference to a handle to the object. Observe that your c++ function will need to dereference the reference in order to get the actual object.

Regards,
Andreas

 

Thanks for the reply, however, I don't think I understand it properly. Let me summarize:

 

1. In AngelScript I will have InitScriptInstance( @this ); as you wrote

 

2. In C++ I will register the function using declaration "void InitScriptInstance( ?&in )", is this still correct?

 

3. The function itself will look like this

void InitScriptInstance( void* pointer, int type )
{
   asIScriptObject* obj = (asIScriptObject*)pointer;
}

 

This does not work, so I guess one of the three steps caused misunderstanding on my side. Would you please care to elaborate?

Thanks

 

P.S.: If I rewrite the 'pointer' getter in the function above like this:

asIScriptObject** obj = (asIScriptObject**)pointer;

the dereference *obj is then NULL.

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1. Correct.

 

2. Correct.

 

3. The function should look something like this:

 

[code]void InitScriptInstance( void *pointer, int typeId ) {   asIScriptObject *obj = 0;   if( (typeId & asTYPEID_OBJHANDLE) && (typeId & asTYPEID_SCRIPTOBJECT) )     obj = *reinterpret_cast<asIScriptObject**>(pointer);   else   {     // The script didn't give us a handle to a script class. Throw an exception     asIScriptContext *ctx = asGetActiveContext();     ctx->SetException("InitScriptInstance require a handle to a script class");     return;   }      // Do something with the object received (remember to increase the reference if the handle is to be stored)    ... }[/code]

 

The obj pointer shouldn't be null with this. If it is then something is wrong, perhaps even a bug in AngelScript.

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