| CODEPTR (or CALLBACK) will return the absolute address of a SUB or FUNCTION.
Syntax: CODEPTR(MySUB)
SUB MySUB
END SUB
A& = CODEPTR(MySUB)
Details:
Use this function for CALLBACK
routines, i.e., when your program responds to Windows messages and
calls your function). Note - there is only ONE CALLBACK/CODEPTR allowed for each function
that uses the same number of parameters. So not all cases
may be implemented unless you use caution. It cannot be set to a a virtual Sub/Function address like a virtual table in C/C++.
Examples:
FUNCTION One (A as LONG) AS LONG
....
END FUNCTION
FUNCTION Two (A as LONG, B as LONG) AS LONG
....
END FUNCTION
FUNCTION Two2 (A as LONG, B as LONG) AS LONG
....
END FUNCTION
In this case CODEPTR(One) is different from CODEPTR(Two)
BUT, the address of CODEPTR(Two) is the same as CODEPTR(Two2) and only the last
function declared is called! Since WndProc uses four parameters you can only have one
WndProc per application:
pOldProc = SetWindowLong(Myhandle,GWL_WNDPROC, CODEPTR(Form.WndProc).
There is a fix using the Callback forwarder code by Jacques
Philip.
See the function gRQ2_SetNewCallBack in RapidQ2 for examples on
how to do this
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