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_Engine_

How use delegates from c++

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Hi!
 
I try to implement passing delegates as arguments from script and call it from c++.
 
i use follow code to store script function - 
 

void ScriptModuleCore::Network::SetDelegate(DelegateAS& delegateAS, asIScriptFunction* cb)
{
   asIScriptEngine* engine = ((ScriptMachine*)(core->Script()->Machine()))->Machine();
 
   if (delegateAS.callback)
   {
     delegateAS.callback->Release();
   }
 
   if (delegateAS.callbackObject)
   {
      engine->ReleaseScriptObject(delegateAS.callbackObject, delegateAS.callbackObjectType);
   }
 
   delegateAS.callback = 0;
   delegateAS.callbackObject = 0;
   delegateAS.callbackObjectType = 0;
 
   if( cb && cb->GetFuncType() == asFUNC_DELEGATE )
   {
      delegateAS.callbackObject     = cb->GetDelegateObject();
      delegateAS.callbackObjectType = cb->GetDelegateObjectType();
      delegateAS.callback           = cb->GetDelegateFunction();
 
      engine->AddRefScriptObject(delegateAS.callbackObject, delegateAS.callbackObjectType);
 
      delegateAS.callback->AddRef();

      cb->Release();
   }
   else
   {
      delegateAS.callback = cb;
   }
} 

follow code executes script function

asIScriptContext* ctx = GrabContext();
	
ctx->Prepare(script_func);			

ctx->SetObject(hack_callbackObject);

ctx->Execute();

All fine when we deal with just function. But if we pass delegate than we got assertion in AngelScript in follow function -

// internal
int asCScriptFunction::GetRefCount()
{
   asASSERT( funcType == asFUNC_DELEGATE );
 
   return externalRefCount.get();
}

Maybe i just doing something wrong when dealing with delegate from c++ or this is bug in AngelScript?

Edited by _Engine_

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When calling the delegate you can just use it like a normal global script function, there is no need to get the script object and class method from the delegate, unless you really want to store these in a different way than the delegate itself (e.g. if you want to use a weakref).

 

 

About the assert failure. Can you show me the callstack where this happened?

 

I suspect the problem is that the asCScriptFunction instance was destroyed prematurely for some reason, and thus the funcType no longer is a asFUNC_DELEGATE when the call to GetRefCount happened even though it originally was. 

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Hi!

 

Looks like problem is - i used delegateAS.callback = cb->GetDelegateFunction(); insteed i must store script function in manner i deal with just callback and i must rise reference count.

 

So now my function with storing scriptfunction looks like:

void ScriptModuleCore::Network::SetDelegate(DelegateAS& delegateAS, asIScriptFunction* cb)
{
	asIScriptEngine* engine = ((ScriptMachine*)(core->Script()->Machine()))->Machine();

	if (delegateAS.callback)
	{
		delegateAS.callback->Release();
	}

	delegateAS.callback = cb;

	if( cb && cb->GetFuncType() == asFUNC_DELEGATE )
	{
		delegateAS.callback->AddRef();
	}
} 

and now works perfect.

 

Thanks for help :)

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To be absolutely correct you should call AddRef on the function regardless if it is a delegate or normal function.

 

Your function should be like this:

 

void ScriptModuleCore::Network::SetDelegate(DelegateAS& delegateAS, asIScriptFunction* cb) 
{ 
  asIScriptEngine* engine = ((ScriptMachine*)(core->Script()->Machine()))->Machine(); 
  if (delegateAS.callback) 
  { 
    delegateAS.callback->Release(); 
  } 
  delegateAS.callback = cb; 
  if (cb) 
  { 
    delegateAS.callback->AddRef(); 
  } 
} 

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