OpenEuphoria

RE: Shared memory

• Posted by Matt Lewis <matthewwalkerlewis at yahoo.com> Dec 15, 2003
• 854 views

Derek Parnell wrote:
> 
> From: "Philip D." <philip1987 at hotmail.com>
> 
> > I really would like to do this because I want to make a program 
> > with the win32lib and have DLLs which can put controls on the 
> > window made with the program.  This currently can't be done 
> > because the DLL has to include a whole fresh set of win32lib 
> > variables.  (see topic: Referencing Control Ids in DLLs)  If I 
> > could share their memory, the DLL would know about the window 
> > created in the program.
> 
> Stop! Read my lips! You can't do this with win32lib. It is NOT 
> built for this. 
> 
> You can either place win32lib in your main program OR put it in the 
> DLL, but you can't do both and have it work how you want to.

Why does everyone say this is impossible?  The key is to set up some 
callback mechanism in your program for the dll to call the correct 
win32lib routines.  You'd need to figure out which routines you wanted 
to call from win32lib.  You'd also want to know ahead of time which 
control id's you'd want to share.  Then set up id's as constant values:

constant
MAIN_WIN = 1,
EDIT_TEXT = 2,
THE_COMBO = 3, -- etc...

CREATE = 1,
SET_FOCUS = 2,
SET_TEXT = 3 -- etc...

In your app, then set up a sequence to hold the values and routine ids:

sequence my_controls, win_routines
my_controls = { main_win, edit_text, the_combo }
win_routines = { routine_id("create"), routine_id("setFocus"),
 routine_id("setText")}

...and a couple of callbacks:

function get_control_id( atom id )
	return my_controls[id]
end function
constant 
GET_OBJECT = define_c_func( my_dll, "get_object",{},E_OBJECT),
SET_OBJECT = define_c_proc( my_dll, "set_object", {E_OBJECT})
function call_win_func( atom routine )
	sequence args
	object return_val
	args = c_func( GET_OBJECT, {})
	return_val = call_func( win_routines[routine], args )
	if atom(return_val) then
		return return_val
	end if
	c_proc( SET_OBJECT, { return_val })
	return -1
end function

Unfortunately, only in calls *to* the dll will you be able to pass 
sequences, which is why you'll have to have functions in the DLL called 
get_object() and set_object() that can return and set the value of a 
local variable.  It's  somewhat complicated, but I don't see why it 
couldn't work.  I may try to code this up as a standalone library...

Matt Lewis