[Grok-dev] Re: SVN: grok/branches/regebro-guido-templates/src/grok/ Template types can now be registered.

[Philipp von Weitershausen]

Lennart Regebro wrote:
> Log message for revision 80472:
>   Template types can now be registered.
>   
> 
> Changed:
>   U   grok/branches/regebro-guido-templates/src/grok/_grok.py
>   U   grok/branches/regebro-guido-templates/src/grok/components.py
>   U   grok/branches/regebro-guido-templates/src/grok/interfaces.py
>   U   grok/branches/regebro-guido-templates/src/grok/templatereg.py
>   U   grok/branches/regebro-guido-templates/src/grok/tests/view/dirandinlinetemplate.py

Neat. May I suggest a slight simplification?

>  class PageTemplateFile(GrokPageTemplate, TrustedAppPT,
>                         pagetemplatefile.PageTemplateFile):
> +    
> +    interface.implements(interfaces.ITemplateFile)

If you add

        interface.classProvides(interfaces.ITemplateFactory)

to this class (note the difference between *provide* and *implement*!), 
then the following definition can go away completely:

> +
> +class PageTemplateFileFactory(grok.GlobalUtility):
> +    
> +    grok.implements(grok.interfaces.ITemplateFactory)
> +    grok.name('pt')
> +    
> +    
> +    def __call__(self, filename, _prefix=None):
> +        return grok.components.PageTemplateFile(filename, _prefix)
> +    

Instead, you would say:

   grok.global_utility(grok.components.PageTemplateFile, name='pt')


Basically, what we're doing is letting the *class* provide the factory 
interface. Classes are obviously callable, so they fulfill that 
ITemplateFactory interface quite well.

It is quite a common pattern to have things like

   class Foo:
       classProvides(IFooFactory)
       implements(IFoo)

We have this for example with vocabularies.


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