Returning Values to AutoLISP Functions

ObjectARX provides a set of functions that enables an external function to return values to AutoLISP. These value-return functions have no AutoLISP counterparts. The following table summarizes these functions.

Value-return function summary
Function Name	Returns
acedRetInt	An integer value
acedRetReal	A real value
acedRetPoint	A 3D point
acedRetStr	A string
acedRetVal	A value passed “generically” in a result buffer
acedRetName	An entity (RTENAME) or selection set (RTPICKS) name (see Selection Set and Entity Names for more information on selection sets and entities)
acedRetT	The AutoLISP value t (true)
acedRetNil	The AutoLISP value nil
acedRetVoid	A blank value: AutoCAD doesn't display the result
acedRetList	A list of result buffers returned to AutoLISP

The following example shows the scheme of a function called when the application receives a kInvkSubrMsg request. It returns a real value to AutoLISP.

int dofun() 
{ 
    ads_real x;
    // Check the arguments and input conditions here.
    // Calculate the value of x.
    acedRetReal(x); 
    return GOOD; 
}

Note: An external function can make more than one call to value-return functions upon a single kInvkSubrMsg request, but the AutoLISP function returns only the value passed it by the last value-return function invoked.