OpenEuphoria

Re: win32lib event handling question

• Posted by Derek Parnell <ddparnell at bigpond.com> Jul 20, 2005
• 478 views

ags wrote:
> 
> Derek Parnell wrote:
> > My argument now is that we should compromise. As routine_id() is a special
> > usage technique,
> > and not one used in common code, it should be allowed to reference routines
> > further
> > down in the source code, but direct references should still stick with the
> > RDS philosophy.
> > People who are coding are smart enough to not be confused by this.
> 
> I think at least a warning of a forward routine_id reference would give you
> the chance to think about other ways of doing it (if possible).  Then again
> maybe we should be checking that routine_id(...) doesn't = -1? 
> eg
> 
> }}}
<eucode>
> -- in include file
> include win32lib.ew
> 
> procedure bad_routine_id()
>    puts(1, "Warning: Bad routine_id used.  Check for forward reference\n")
> -- and "Sorry but I can't tell you where it is" 
> end procedure
> global constant rid_Bad_routine = routine_id("bad_routine_id")
> 
> global function safe_routine_id(sequence code_name)
>    return w32iff(routine_id(code_name), routine_id(code_name),
>    rid_Bad_routine)
>    -- that's if -1 is false? otherwise if.. then..
> end function
> 
> -- in code
> procedure Window1_onMouse()
>    VOID = message_box("The mouse moved!!", "Important", MB_OK)
> end procedure
> setHandler(Button1, w32HMouse, safe_routine_id("Window1_onMouse") )
> <font color="#330033"></eucode>
{{{
</font>
> 
> And with safe_routine_id() in an early included header most functions
> /procedures would be visible anyway wouldn't they?

Actually that turns out not to be the case. When the routine_id() is executed,
the string passed to it will be the name of a routine that occurs further down in
the source code and thus invisible to routine_id. The way to deal with this is
convoluted and totally obtuse ...

-- in code
global atom rid_safe_routine_id

include win32lib.ew
procedure Window1_onMouse()
   VOID = message_box("The mouse moved!!", "Important", MB_OK)
end procedure
setHandler(Button1, w32HMouse, 
      call_func(rid_safe_routine_id,{"Window1_onMouse"}) )

include saferid.e -- *MUST* be and the end of the main code file.

The content of saferid.e would be like ...

procedure bad_routine_id()
   puts(1, "Warning: Bad routine_id used.  Check for forward reference\n")
-- and "Sorry but I can't tell you where it is" 
end procedure
global constant rid_Bad_routine = routine_id("bad_routine_id")

global function safe_routine_id(sequence code_name)
   return w32iff(routine_id(code_name), routine_id(code_name), rid_Bad_routine)
   -- that's if -1 is false? otherwise if.. then..
end function
rid_safe_routine_id = routine_id("safe_routine_id")

Its the physical order of the lines of code that matters, and not which order
they are executed in.

-- 
Derek Parnell
Melbourne, Australia
Skype name: derek.j.parnell