Started documentation for blueprints

docs/blueprints.rst

@@ -0,0 +1,43 @@
+.. _blueprints:
+
+Modular Applications with Blueprints
+====================================
+
+.. versionadded:: 0.7
+
+Flask knows a concept known as “blueprints” which can greatly simplify how
+large applications work.  A blueprint is an object works similar to an
+actual :class:`Flask` application object, but it is not actually an
+application.  Rather it is the blueprint of how to create an application.
+Think of it like that: you might want to have an application that has a
+wiki.  So what you can do is creating the blueprint for a wiki and then
+let the application assemble the wiki on the application object.
+
+Why Blueprints?
+---------------
+
+Why have blueprints and not multiple application objects?  The utopia of
+pluggable applications are different WSGI applications and merging them
+together somehow.  You can do that (see :ref:`app-dispatch`) but it's not
+the right tool for every case.  Having different applications means having
+different configs.  Applications are also separated on the WSGI layer
+which is a lot lower level than the level that Flask usually operates on
+where you have request and response objects.
+
+Blueprints do not necessarily have to implement applications.  They could
+only provide filters for templates, static files, templates or similar
+things.  They share the same config as the application and can change the
+application as necessary when being registered.
+
+The downside is that you cannot unregister a blueprint once application
+without having to destroy the whole application object.
+
+The Concept of Blueprints
+-------------------------
+
+The basic concept of blueprints is that they record operations that should
+be executed when the blueprint is registered on the application.  However
+additionally each time a request gets dispatched to a view that was
+declared to a blueprint Flask will remember that the request was
+dispatched to that blueprint.  That way it's easier to generate URLs from
+one endpoint to another in the same module.

docs/contents.rst.inc

@@ -18,6 +18,7 @@ instructions for web development with Flask.
    config
    signals
    reqcontext
+   blueprints
    shell
    patterns/index
    deploying/index