Re: [Boost-users] Connecting Windows Messages/Events with Boostcallbacks

Subject: Re: [Boost-users] Connecting Windows Messages/Events with Boostcallbacks
From: asif saeed (asif.lse2_at_[hidden])
Date: 2011-03-25 00:52:00

Hi Andrew,

Thank you for giving me a good example. Though I haven't yet bothered to
look into the SmartWin++ source code but I suspect they have done something
more smarter.

Thank you all.

-Asif

On Thu, Mar 24, 2011 at 7:12 PM, Andrew Holden <
aholden_at_[hidden]> wrote:

> On Thursday, March 24, 2011 8:42 AM, Igor R wrote:
> >> Using your approach, I need to use a case statement inside a message
> loop.
> >
> > As you can see, struct Handler in my example doesn't have any case
> statements
> > as well.
> > Again: the basic, lowlevel message processing is hidden - in my
> example in the
> > "button" class, in smart win++ somewhere in WidgetWindow or its base
> classes.
> > The *users* of the framework do not need to deal with messages as the
> > framework exposes higher-level facilities.
>
> Perhaps you can replace the switch statement with a map or similar
> (warning: untested):
>
> typedef std::map <UINT, boost::signals2::signal <LRESULT (HWND, UINT,
> WPARAM, LPARAM)> MessageMap;
> MessageMap message_map;
>
> LRESULT CALLBACK WindowProc(
>  __in  HWND hwnd,
>  __in  UINT uMsg,
>  __in  WPARAM wParam,
>  __in  LPARAM lParam
> )
> {
>        MessageMap::const_iterator handler = message_map.find (uMsg);
>        if (handler != message_map.end())
>        {
>                return handler->second (hwnd, uMsg, wParam, lParam);
>        }
>        else
>        {
>                return DefWindowProc (hwnd, uMsg, wParam, lParam);
>        }
> }
>
> You could then insert any handler for any message into message_map.  I'm
> not sure what combiner would be most appropriate here.  There is also
> the question of where message_map should really go.  A global variable
> (as my example implies) probably isn't the best place.
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