Added URL config documentation

git-svn-id: http://code.djangoproject.com/svn/django/trunk@70 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/url_dispatch.txt

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+============
+URL dispatch
+============
+
+We're fanatics about good URLs.  No ".php" or ".cgi", and certainly not any of
+that "0,2097,1-1-1928,00" nonsense.  Django's URL dispatch lets you design
+your URLs to be as pretty as the rest of your application.
+
+See `the Django overview`_ for a quick introduction to URL dispatch; this
+document will continue on from there.
+
+.. _`the Django overview`: http://www.djangoproject.com/documentation/overview/#design-your-urls
+
+The view prefix
+===============
+
+Here's the example from that overview::
+
+    from django.conf.urls.defaults import *
+    
+    urlpatterns = patterns('',
+        (r'^/articles/(?P\d{4})/$',                   'myproject.news.views.articles.year_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/$',         'myproject.news.views.articles.month_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/$',         'myproject.news.views.articles.month_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'myproject.news.views.articles.article_detail'),
+    )
+    
+You can see that the first argument to ``patterns`` is an empty string in the
+above example, but it's actually very useful.  The first argument will be
+prepended to all the view functions in the urlpatterns list, so the above 
+example could be written more concisely as::
+
+    urlpatterns = patterns('myproject.news.views.articles',
+        (r'^/articles/(?P\d{4})/$',                   'year_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/$',         'month_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/$',         'month_archive'),
+        (r'^/articles/(?P\d{4})/(?P\d{2})/(?P\d+)/$', 'article_detail'),
+    )
+
+Including other URL configs
+===========================
+
+You can also "include" other URL config modules at any point along the path. 
+This is essence "roots" a set of URLs below other ones.  This is most often used
+for a site's "base" URL config; the ``ROOT_URLCONF`` setting points to a urlconf
+module that will be used for the entire site.  This is the URL config for the
+`Django website`_ itself which includes a number of other URL config modules::
+
+    from django.conf.urls.defaults import *
+    
+    urlpatterns = patterns('',
+        (r'^weblog/',        include('django_website.apps.blog.urls.blog')),
+        (r'^documentation/', include('django_website.apps.docs.urls.docs')),
+        (r'^comments/',      include('django.contrib.comments.urls.comments')),
+        (r'^rss/',           include('django.conf.urls.rss')),
+        (r'',                include('django.conf.urls.flatfiles')),
+    )
+    
+.. _`Django website`: http://www.djangoproject.com/
+
+Passing extra options to view functions
+=======================================
+
+There are two ways of passing arguments into your view functions: named captures
+from the regex (which you've already seen) and the optional third element
+in url config tuples.  This third element can be a dictionary of extra
+keyword arguments that will be passed to the view function::
+
+    urlpatterns = patterns('myproject.news.views.articles',
+        (r'^/articles/(?P\d{4})/$', 'year_archive', {key: value, key2: value 2}),
+    )
+
+This is especially useful for `generic view functions`_.
+
+.. _`generic view functions`: http://www.djangoproject.com/documentation/generic_views/