[Zope3-dev] Re: wading through zcml...

[Martijn Faassen]

Philipp von Weitershausen <philipp at weitershausen.de> wrote:
[Chris]
>> That said, I can live with most of the crap, but these dynamically 
>> generated classes... wtf? why? why did that? why are they still breathing?!
> 
> *sigh* I don't know who came up with the idea, and I don't really care 
> as I don't want to point fingers at anyone. The reasons are probably 
> historical...

Philipp, note that we're dynamically generating some classes in
Grok:

dynamically generated class for templates that don't have classes of
themselves. I know you were there when we created this one. :)

        class TemplateView(grok.View):
            template = unassociated
            module_info = module_info_

of course the instances of this class do nothing the developer has to
interact with. As soon as the developer provides a view class of their
own, there's no dynamically generated class anymore. I think that this
is an acceptable use of the pattern.
 
I've done it too recently in the form support. The *real* formlib-level
form class is dynamically created for each grok-level form:

    class RealEditForm(form.EditForm):
        form_fields = get_form_fields(factory, context)
        actions = actions_

This one is a bit more scary, as the end-user interacts with an
*instance* of this class; the form attribute on grok-level forms is one.

Of course there were good reasons to do this - I wanted to avoid
mixing formlib level forms with grok-level forms, as too many method
names were the same and making that horrible tangle work would've been
a lot more pain indeed, I think.

Regards,

Martijn