Re: [boost] Re: GUI Library Proposal for a Proposal

From: John Torjo (john.lists_at_[hidden])
Date: 2004-11-12 14:56:54

Mathew Robertson wrote:

>>>The FOX GUI has exactly this capability, you can connect a variable directly to the widget, without requiring any glue code at all.  In fact, you can connect the same variable to multiple widgets at the same time (eg a 'spinner' widget and an 'editeline'), without requiring the programmer to write any type of callback mechanism.
>>>
>>>This works because all GUI events are bi-directional.  For more information, read: http://www.fox-toolkit.org/datatarget.html
>>>
>>
>>That seems a lot of code, compared to:
>>http://www.torjo.com/win32gui/save_dlg.html
>>Not to say about validation...
> 
> 
> The problem with this implementation is that the 'user_name' field cannot (usually) 
> connect to more than one widget at a time.

That is a current limitation, but I don't think you need it so much.
Anyway, you can work around it, by listening to kill_focus events:
- you will have temporary variables, and each is bound to a control.
- You listen for kill_focus from these variables
- on kill_focus, you synchronize the temporary variables

> 
> Also, most widget libraries dont allow you to connect a variable to a widget, 
>and still allow user validation.  This is because the widget library 
 > doesn't callback into the validation code,
> since it assumes that if it is connected to a widget, then no validation code is necessary.
> 

That's the win32gui' advantage :)

"if it is connected to a widget, then no validation code is necessary." 
- that really sounds silly.

Best,
John

-- 
John Torjo,    Contributing editor, C/C++ Users Journal
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