>Hi,
>
>I need to check return values of many API function calls within class. In order to simplify this task I have the following idea: assign a return value to a property of a class and test a value in Assign method for that property.
>

>Define Class test as Custom
>	Protected RetVal
>	Protected Procedure RetVal_Assign(tnRetVal)
>		If tnRetVal != 0
>			Error "Error #" + Trans(tnRetVal)
>		EndIf
>	EndProc
>	Procedure SomeMethod()
>		This.RetVal = SomeAPIFunction()
>	EndProc
>EndDefine
>

>However this code will generate an error within line with Error statement, but I want to generate an error within line where API function is called. Any ideas?
>
>TIA,
>Alexander

Further ... try something like

cErrorCommand = "ERROR "+ALLTRIM(STR(nErrorNummer))+" "+cErrorArgument
RETURN &cErrorCommand

You (well I ...) never know what happens ...

Or approached from the other side

&This.RetVal = SomeAPIFunction()

the return value or filled with "" (hence no command to perform) or the Error command. I don't know how to deal with the real return value though.
But I'd say here lay the possibilities.