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1 parent 5190f60 commit b39dcef270e64dfce860d14b8cadc25694a64255 @tseaver tseaver committed Sep 17, 2012
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  1. +27 −0 configuration/whirlwind_tour.rst
@@ -1,6 +1,9 @@
A Whirlwind Tour of Advanced Pyramid Configuration Tactics
+Concepts: Configuration, Directives, and Statements
This article attempts to demonstrate some of Pyramid's more advanced
startup-time configuration features. The stuff below talks about
"configuration", which is a shorthand word I'll use to mean the state that is
@@ -134,6 +137,9 @@ configuration happens before any view configuration at commit time. If a
view references a nonexistent route, an error will be raised at commit time
rather than at configuration statement execution time.
+Sanity Checks
We can see this sanity-checking feature in action in a failure case. Let's
change our application, commenting out our call to ``config.add_route()``
temporarily within ````:
@@ -181,6 +187,9 @@ It's telling us that we attempted to add a view which references a
nonexistent route. Configuration directives sometimes introduce
sanity-checking to startup, as demonstrated here.
+Configuration Conflicts
Let's change our application once again. We'll undo our last change, and add
a configuration statement that attempts to add another view:
@@ -254,6 +263,9 @@ other in this circumstance; it can't serve both. So rather than trying to
guess what you meant, Pyramid raises a configuration conflict error and
refuses to start.
+Resolving Conflicts
Obviously it's necessary to be able to resolve configuration conflicts.
Sometimes these conflicts are done by mistake, so they're easy to resolve.
You just change the code so that the conflict is no longer present. We can
@@ -363,6 +375,9 @@ callback overwrote the view configuration added by the first commit.
Calling ``config.commit()`` is a brute-force way to resolve configuration
+Including Configuration from Other Modules
Now that we have played around a bit with configuration that exists all in
the same module, let's add some code to ```` that causes configuration
that lives in another module to be *included*. We do that by adding a call
@@ -446,6 +461,9 @@ just import the moreconfiguration function from ``another`` and call it directly
the configurator!" You're mostly right. However, ``config.include()`` does
more than that. Please stick with me, we'll get to it.
+The :func:`includeme` Convention
Now, let's change our ```` slightly. We'll change the
``config.include()`` line in ```` to include a slightly different
@@ -498,6 +516,9 @@ Pyramid convenience shorthand: if you tell Pyramid to include a Python
``config.include('amodule')`` always means
+Nested Includes
Something which is included can also do including. Let's add a file named
```` next to
@@ -535,6 +556,9 @@ When we start up this application, we can visit ``/``, ``/goodbye`` and
which includes ````. You can nest configuration includes within
configuration includes ad infinitum. It's turtles all the way down.
+Automatic Resolution via Includes
As we saw previously, it's relatively easy to manually resolve configuration
conflicts that are produced by mistake. But sometimes configuration
conflicts are not injected by mistake. Sometimes they're introduced on
@@ -595,6 +619,9 @@ just factoring your configuration into functions and arranging to call those
functions at startup time directly. Using ``config.include()`` makes
automatic conflict resolution work properly.
+Custom Configuration Directives
A developer needn't satisfy himself with only the directives provided by
Pyramid like ``add_route`` and ``add_view``. He can add directives to the
Configurator. This makes it easy for him to allow other developers to add

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