Windows API: Calling procedures by reference or address 2003-12-01 -- Jim Kane Newsgroups: softvelocity.clarion.language
The way I do it is like this:
Map
MethodIWantToClassStatic procedure(long lpMyClass,Long Parameter1),pascal
someprocedure(long lpStatic, long lpClass)
End
Class MyClassType, Type
init procedure()
kill procedure()
MethodIWantToCall(long parameter1)
end
MyClass MyClasstype
code
someprocedure(address(MethodIwanttoClassStatic), address(myClass))
someprocedure procedure(long lpStatic, long lpMyClass)
code
calldllcl.init('',1)
calldllcl.callbyaddress(lpStatic, lpMyClass, valueof parameter1)
calldllcl.kill()
MethodIWantToCallStatic procedure (long lpMyClass, long parameter1) !,pascal
loc:myclass &MyClassType
code
loc:MyClass&=(lpMyClass)
loc:myClass.MethodIwanttocall(long parameter1)
return
I use my calldllcl from clarion mag and use lpMethodIWantToCall to call
MethodIWantToCallStatic from anywhere and it either does something directly
or calls the class method for me. There may be some easier way but this has
been highly reliable and most of the time I dont really use the static
procedure to call the class method but instead just do the work in the
static procedure.
Jim kane
> I know how to pass the name of a procedure to another procedure so the
> called procedure can call the named procedure.
>
> Now I need to store a pointer or reference to the named procedure so
> that a different procedure in the class can use the pointer to call
> the named procedure. It's not clear from the Clarion 6 language
> reference manual how to do this (or if it can even be done).
>
> Also, it's not clear how to prototype the procedure parameter so that
> the named procedure can be a method of another class. The language
> reference manual indicates that a class method has an implicit first
> parameter which is "self".
>
> Maybe an example of what I want to do will help.
>
> I will have a class method defined as
> class(PGLF)
> VarLookup PROCEDURE(*string varname),string
> end
>
> When I initialize my report parser I will make a call something like
> SRPG.SetVarCallback(PGLF.VarLookup)
> The SetVarCallback procedure will have to store the pointer.
>
> Then in SRPG.GetField, I will make a call to the procedure via the
> pointer.
>
> Normally I would prototype this as
>
> PT_ReportVarFunction FUNCTION(*string varname),STRING,TYPE
>
> class(SRPG)
> SetVarCallback(*PT_ReportVarFunction pCallbackFunc)
> end
>
> But the two questions I have are
>
> 1) How do I declare a member variable in class SRPG to store the value
> from pCallbackFunc? Is this even possible?
>
> 2) Do I need to modify PT_ReportVarFunction to allow for a member
> method from another class to be passed as in the example above? If so,
> how?
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