[stringtemplate-interest] Multimethods

[Terence Parr]

On Nov 14, 2008, at 6:17 AM, Roman Odaisky wrote:

> Hi,
>
>> your template could be
>>
>> blog_post(m,d,y) ::= "/y/m/d&sessionid=<session.ID>"
>> or whatever the field of the session is. would that work?
>
> That would work. But that would cause unnecessary duplication.

  duplication of what?

> Django has a thing called URLconf[1] which allows one to bind URLs to
> functions by means of regular expressions. Moreover, it allows one to
> determine a URL that would cause a given function to get called with  
> given
> arguments.
>
> For example, if a URLconf entry looks like this:
>
> (r"^/(?P<year>\d+)/(?P<month>\d+)/(?P<day>\d+)$", posts_by_date)
>
> then Django would call posts_by_date(request, year=2008, month=11,  
> day=14).
> And when one calls reverse(posts_by_date, year=2008, month=11,  
> day=14), one
> gets "/2008/11/14". So one line in a configuration file works both  
> ways. If I
> were to create a template like the one you suggested above, it would
> duplicate the information that is already known to the application.

Well, this is really a controller issue. Technically URLs must be  
computed by the controller and sent in as data to the view. However we  
want to fudge this to make it convenient is fine.

> I need to have an option to use that system. Adding a  
> get_absolute_url method
> to objects works as long as the URL depends only on one object, but  
> recently
> I’ve encountered URLs that need more than one. At the moment I’m  
> using hacks
> like $o1.url_for_o2.(o2.id)$ where get_url_for_o2() returns an  
> object with
> operator [] overloaded.

Add a renderer for that object and then use a format option to select?

> Do you have anything against explicit adding of templates that call  
> functions
> like I proposed in the first message?

Yes, I'm afraid, because then $f()$ can call it arbitrary function.

T
>
>
> References:
> [1] http://docs.djangoproject.com/en/dev/intro/tutorial03/#design-your-urls
>
> -- 
> WBR
> Roman.
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