[M3devel] small design problem in ButtonVBT?

[Olaf Wagner]

Though I promised to do it, I have lost sight of this task while
trying to build some RC3 archives on Windows. As I'm not at home this
evening, can somebody else please commit Hendrik's extension?

Is this something we should should have in the release branch, too?
Probably not necessary?

Olaf

Quoting hendrik at topoi.pooq.com:

> On Wed, Apr 01, 2009 at 12:03:47PM +0200, Olaf Wagner wrote:
>> Quoting hendrik at topoi.pooq.com:
>>
>> >The BottonVBT contains an action, which is a procedure rather than a
>> >method. b This makes it awkward to subclass ButtonVBT becaue the action
>> >will still expect its first parameter to be a ButtonVBT instead of
>> >belonging to the subclass, and an explicit downcast of some sort will be
>> >needed to acess the subclass's members.
>> >
>> >The Trestle manual says this was a deliberate decision:
>> >
>> >: The action procedure is a field rather than a method in order to allow
>> >: buttons with different action procedures to share their method suites.
>> >
>> >I, however, find it massively inconvenient because it mans I have to
>> >resort to downcasting or the very kludgey VBT.GetProp to access what
>> >should be just there.  I'd rather the action procedure was a method.
>> >
>> >But it should be possible to have the best of both worlds.  Have an
>> >action2 (better name wanted here) method that is available for
>> >overriding, and by default calls the procedure in the existing action.
>> >field.  That action2 method wounl then be called by Trestle wherever
>> >action is now called.
>> >
>> >Does anyone see problems with this?
>>
>> Sounds fine to me offhand. You should test your extensions with
>> some of the existing larger applications, like mentor and Juno-2,
>> of course.
>
> OK. Here's the patch.  Would it be possible for someone to check it in
> for me?
>
> mentor runs fine with this change; I watched it animate a heap-sort.
>
> I have no idea what Juno is supposed to do, but it did respond to
> button-pushes.
>
>
> hendrik at lovesong:~/cm3/love-sq/cm3/m3-ui/ui/src/split$ cvs diff
> cvs diff: Diffing .
> Index: ButtonVBT.i3
> ===================================================================
> RCS file: /usr/cvs/cm3/m3-ui/ui/src/split/ButtonVBT.i3,v
> retrieving revision 1.2
> diff -r1.2 ButtonVBT.i3
> 39a40
>>     act(READONLY cd: VBT.MouseRec);
> Index: ButtonVBT.m3
> ===================================================================
> RCS file: /usr/cvs/cm3/m3-ui/ui/src/split/ButtonVBT.m3,v
> retrieving revision 1.2
> diff -r1.2 ButtonVBT.m3
> 28c28,29
> <     init := Be
> ---
>>     init := Be;
>>     act := act
> 46a48,52
>> PROCEDURE act(v : T; READONLY cd: VBT.MouseRec) =
>>   BEGIN
>>     v.action(v, cd);
>>   END act;
>>
> 59c65
> <         v.action(v, cd);
> ---
>>         v.act(cd);
> hendrik at lovesong:~/cm3/love-sq/cm3/m3-ui/ui/src/split$
>
> -- hendrik
>



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