[wxpython-dev] Google SoC Project - MVC

Hi Keith,

My suggestion is to investigate Cells technology (pycells and Trellis)
integration with wxPython

Peter

On Wed, May 28, 2008 at 8:41 AM, Keith Holman <[email protected]> wrote:

> Hello wxpython-dev,
>
> My name is Keith Holman, and as part of my Google Summer of Code project I
> will be working on improving wxPython so that users of the library can
> better separate their data models from their presentation logic
> (Model-View-Controller). Please contact me on the #wxwidgets channel or by
> email if there's anything in particular that you think I should look into.
>
> Thanks for your time!
>
> Keith Holman
>
>
> My project:
> http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4
> My email: [email protected]
> IRC nickname: holmak
>
> _______________________________________________
> wxpython-dev mailing list
> [email protected]
> http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev
>
>


--
There is NO FATE, we are the creators.
Hi Keith,<br><br>My suggestion is to investigate Cells technology (pycells and Trellis) integration with wxPython<br><br>Peter<br><br><div class="gmail_quote">On Wed, May 28, 2008 at 8:41 AM, Keith Holman &lt;<a href="mailto:cobalt037@gmail.com">cobalt037@gmail.com</a>&gt; wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hello wxpython-dev,<br><br>My name is Keith Holman, and as part of my Google Summer of Code project I will be working on improving wxPython so that users of the library can better separate their data models from their presentation logic (Model-View-Controller). Please contact me on the #wxwidgets channel or by email if there&#39;s anything in particular that you think I should look into.<br>

<br>Thanks for your time!<br><br>Keith Holman<br><br><br>My project: <a href="http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4" target="_blank">http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4</a><br>

My email: <a href="mailto:cobalt037@gmail.com" target="_blank">cobalt037@gmail.com</a><br>IRC nickname: holmak<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>There is NO FATE, we are the creators.
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Hi Peter,

On May 29, 2008, at 1:57 AM, Peter Damoc wrote:

> Hi Keith,
>
> My suggestion is to investigate Cells technology (pycells and
> Trellis) integration with wxPython

Definitely worth taking a look at, but I think a better approach would
be to simply allow wxPython controls to take a model and controller,
and use them when set. This way we're not trying to re-invent wxPython
or trying to get fundamentally different frameworks with different
design philosophies and target audiences to try and play nice
together. We're just extending it to be MVC-friendly. We can use
something like wx.lib.pubsub to send notifications when either the
model or the view changes, and the controller sets up listeners for
these events and handles any changes that needs made.

Regards,

Kevin

>
> Peter
>
> On Wed, May 28, 2008 at 8:41 AM, Keith Holman <[email protected]>
> wrote:
> Hello wxpython-dev,
>
> My name is Keith Holman, and as part of my Google Summer of Code
> project I will be working on improving wxPython so that users of the
> library can better separate their data models from their
> presentation logic (Model-View-Controller). Please contact me on the
> #wxwidgets channel or by email if there's anything in particular
> that you think I should look into.
>
> Thanks for your time!
>
> Keith Holman
>
>
> My project: http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4
> My email: [email protected]
> IRC nickname: holmak
>
> _______________________________________________
> wxpython-dev mailing list
> [email protected]
> http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev
>
>
>
>
> --
> There is NO FATE, we are the creators.
> _______________________________________________
> wxpython-dev mailing list
> [email protected]
> http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev

<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Peter,<div><br><div><div>On May 29, 2008, at 1:57 AM, Peter Damoc wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi Keith,<br><br>My suggestion is to investigate Cells technology (pycells and Trellis) integration with wxPython</blockquote><div><br></div><div>Definitely worth taking a look at, but I think a better approach would be to simply allow wxPython controls to take a model and controller, and use them when set. This way we're not trying to re-invent wxPython or trying to get fundamentally different frameworks with different design philosophies and target audiences to try and play nice together. We're just extending it to be MVC-friendly. We can use something like wx.lib.pubsub to send notifications when either the model or the view changes, and the controller sets up listeners for these events and handles any changes that needs made.&nbsp;</div><div><br></div><div>Regards,</div><div><br></div><div>Kevin</div><br><blockquote type="cite"><br>Peter<br><br><div class="gmail_quote">On Wed, May 28, 2008 at 8:41 AM, Keith Holman &lt;<a href="mailto:cobalt037@gmail.com">cobalt037@gmail.com</a>> wrote:<br> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hello wxpython-dev,<br><br>My name is Keith Holman, and as part of my Google Summer of Code project I will be working on improving wxPython so that users of the library can better separate their data models from their presentation logic (Model-View-Controller). Please contact me on the #wxwidgets channel or by email if there's anything in particular that you think I should look into.<br> <br>Thanks for your time!<br><br>Keith Holman<br><br><br>My project: <a href="http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4" target="_blank">http://code.google.com/soc/2008/wxpython/appinfo.html?csaid=4D381307376131D4</a><br> My email: <a href="mailto:cobalt037@gmail.com" target="_blank">cobalt037@gmail.com</a><br>IRC nickname: holmak<br> <br>_______________________________________________<br> wxpython-dev mailing list<br> <a href="mailto:wxpython-dev@lists.wxwidgets.org">wxpython-dev@lists.wxwidgets.org</a><br> <a href="http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev" target="_blank">http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev</a><br> <br></blockquote></div><br><br clear="all"><br>-- <br>There is NO FATE, we are the creators. _______________________________________________<br>wxpython-dev mailing list<br><a href="mailto:wxpython-dev@lists.wxwidgets.org">wxpython-dev@lists.wxwidgets.org</a><br>http://lists.wxwidgets.org/mailman/listinfo/wxpython-dev<br></blockquote></div><br></div></body></html>_______________________________________________
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Am 30.05.2008, 07:41 Uhr, schrieb Kevin Ollivier <[email protected]>:

> Hi Peter,
>
> On May 29, 2008, at 1:57 AM, Peter Damoc wrote:
>
>> Hi Keith,
>>
>> My suggestion is to investigate Cells technology (pycells and
>> Trellis) integration with wxPython
>
> Definitely worth taking a look at, but I think a better approach would
> be to simply allow wxPython controls to take a model and controller,
> and use them when set. This way we're not trying to re-invent wxPython
> or trying to get fundamentally different frameworks with different
> design philosophies and target audiences to try and play nice
> together. We're just extending it to be MVC-friendly. We can use
> something like wx.lib.pubsub to send notifications when either the
> model or the view changes, and the controller sets up listeners for
> these events and handles any changes that needs made.

I am doing the same for FloatCanvas. Internally I wrote a little "event
manager" which just wraps wx.lib.pubsub so it can be replaced with another
implementation if desired. One of the problems I encountered while doing
this is that topics are supposed to be only strings. This seems to be a
problem, because if I want to subscribe only for the updates of a specific
object it's not (cleanly) possible.

Doing something like

obj = createSomeModelWhichSendsEventsWhenItChanges()
Publisher().subscribe( (obj,), obj_all_messages_handler )
Publisher().subscribe( (obj, 'sizeChanged'), obj_size_changed_handler )

is not possible right now. Maybe you could set the topic to
(str(id(obj)),), but that doesn't seem like a clean solution. I am also
wondering whether this would work at all for the default wxPython objects,
because you might get different objs for the same underlying C++ object.
Of course not using any of these objects doesn't create the problem.

I can see three solutions:

1) Patch pubsub so that it allows non-strings to be used.
2) Don't make publisher a singleton. Instead use it something like

obj = createSomeModelWhichSendsEventsWhenItChanges()
obj.subscribe( '', obj_all_messages_handler )
obj.subscribe( 'sizeChanged', obj_size_changed_handler )

or

obj = createSomeModelWhichSendsEventsWhenItChanges()
obj.events.subscribe( '', obj_all_messages_handler )
obj.events.subscribe( 'sizeChanged', obj_size_changed_handler )

This also involves changing pubsub. Either you'd have to inherit from
Publisher or create an attribute from Publisher or you inherit from a
helper class that provides the same subscribe/sendMessage methods and
forwards them to the global publisher by prepending (obj,) which is
basically 1).

3) Use a third-party module like pydispatcher/louie
( http://pydispatcher.sourceforge.net/ ). The advantage here is that
pydispatcher seems quite robust to me (used it for years without issues)
and pubsub doesn't look like it's used all that much and so there are
probably still some bugs lurking. It also supports using arbitrary
subscribers (not only functions that take a single argument) with keywords
and arbitrary topics.
The disadvantages here is that it doesn't support something like a topic
tree out of the box (though I think this is possible by connecting one
event to an other via a function - so you could connect 'sports/baseball'
to 'sports'). The whole thing also happens in a single module instead of a
class, so there's only one pydispatcher for everything. The approach in 2)
could be faked with it though (just make subscribe prepend (obj,) in front
of the topic.
Maybe there are other observer/observable design pattern implementations
in python which I am not familiar with and which could be useful here.

What's your opinion on solving this?

-Matthias
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