merge feature.introspection branch

10 files changed, 1015 insertions, 82 deletions

diff --git a/docs/api/config.rst b/docs/api/config.rst
index a8c193b60..dbfbb1761 100644
--- a/docs/api/config.rst
+++ b/docs/api/config.rst
@@ -94,6 +94,23 @@
 
      .. automethod:: set_renderer_globals_factory(factory)
 
+     .. attribute:: introspectable
+
+        A shortcut attribute which points to the
+        :class:`pyramid.registry.Introspectable` class (used during
+        directives to provide introspection to actions).
+
+        This attribute is new as of :app:`Pyramid` 1.3.
+
+     .. attribute:: introspector
+
+        The :term:`introspector` related to this configuration.  It is an
+        instance implementing the :class:`pyramid.interfaces.IIntrospector`
+        interface.  If the Configurator constructor was supplied with an
+        ``introspector`` argument, this attribute will be that value.
+        Otherwise, it will be an instance of a default introspector type.
+
+        This attribute is new as of :app:`Pyramid` 1.3.
 
   .. attribute:: global_registries
 
diff --git a/docs/api/interfaces.rst b/docs/api/interfaces.rst
index b336e549d..5b190b53b 100644
--- a/docs/api/interfaces.rst
+++ b/docs/api/interfaces.rst
@@ -68,3 +68,11 @@ Other Interfaces
   .. autointerface:: IResponse
      :members:
 
+  .. autointerface:: IIntrospectable
+     :members:
+
+  .. autointerface:: IIntrospector
+     :members:
+
+  .. autointerface:: IActionInfo
+     :members:
diff --git a/docs/api/registry.rst b/docs/api/registry.rst
index 4d327370a..25192f3ed 100644
--- a/docs/api/registry.rst
+++ b/docs/api/registry.rst
@@ -14,3 +14,33 @@
      accessed as ``request.registry.settings`` or
      ``config.registry.settings`` in a typical Pyramid application.
 
+    .. attribute:: introspector
+
+     When a registry is set up (or created) by a :term:`Configurator`, the
+     registry will be decorated with an instance named ``introspector``
+     implementing the :class:`pyramid.interfaces.IIntrospector` interface.
+     See also :attr:`pyramid.config.Configurator.introspector``.
+
+     When a registry is created "by hand", however, this attribute will not
+     exist until set up by a configurator.
+
+     This attribute is often accessed as ``request.registry.introspector`` in
+     a typical Pyramid application.
+
+     This attribute is new as of :app:`Pyramid` 1.3.
+
+.. class:: Introspectable
+
+   The default implementation of the interface
+   :class:`pyramid.interfaces.IIntrospectable` used by framework exenders.
+   An instance of this class is is created when
+   :attr:`pyramid.config.Configurator.introspectable` is called.
+
+   This class is new as of :app:`Pyramid` 1.3.
+
+.. class:: noop_introspector
+
+   An introspector which throws away all registrations, useful for disabling
+   introspection altogether (pass as ``introspector`` to the
+   :term:`Configurator` constructor).
+
diff --git a/docs/glossary.rst b/docs/glossary.rst
index 0d69fbb0d..399b78cdf 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -563,9 +563,8 @@ Glossary
      also `PEP 318 <http://www.python.org/dev/peps/pep-0318/>`_.
 
    configuration declaration
-     An individual method call made to an instance of a :app:`Pyramid`
-     :term:`Configurator` object which performs an arbitrary action, such as
-     registering a :term:`view configuration` (via the
+     An individual method call made to a :term:`configuration directive`,
+     such as registering a :term:`view configuration` (via the
      :meth:`~pyramid.config.Configurator.add_view` method of the
      configurator) or :term:`route configuration` (via the
      :meth:`~pyramid.config.Configurator.add_route` method of the
@@ -941,3 +940,40 @@ Glossary
      directory of a Python installation or virtualenv as the result of
      running ``setup.py install`` or ``setup.py develop``.
 
+   introspector
+     An object with the methods described by
+     :class:`pyramid.interfaces.IIntrospector` that is available in both
+     configuration code (for registration) and at runtime (for querying) that
+     allows a developer to introspect configuration statements and
+     relationships between those statements.
+
+   conflict resolution
+     Pyramid attempts to resolve ambiguous configuration statements made by
+     application developers via automatic conflict resolution.  Automatic
+     conflict resolution is described in
+     :ref:`automatic_conflict_resolution`.  If Pyramid cannot resolve
+     ambiguous configuration statements, it is possible to manually resolve
+     them as described in :ref:`manually_resolving_conflicts`.
+
+   configuration directive
+     A method of the :term:`Configurator` which causes a configuration action
+     to occur.  The method :meth:`pyramid.config.Configurator.add_view` is a
+     configuration directive, and application developers can add their own
+     directives as necessary (see :ref:`add_directive`).
+
+   action
+     Represents a pending configuration statement generated by a call to a
+     :term:`configuration directive`.  The set of pending configuration
+     actions are processed when :meth:`pyramid.config.Configurator.commit` is
+     called.
+
+   discriminator
+     The unique identifier of an :term:`action`.
+
+   introspectable
+      An object which implements the attributes and methods described in
+      :class:`pyramid.interfaces.IIntrospectable`.  Introspectables are used
+      by the :term:`introspector` to display configuration information about
+      a running Pyramid application.  An introspectable is associated with a
+      :term:`action` by virtue of the
+      :meth:`pyramid.config.Configurator.action` method.
diff --git a/docs/index.rst b/docs/index.rst
index e4de8b0c8..ceb29d108 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -65,6 +65,7 @@ Narrative documentation in chapter form explaining how to use
    narr/configuration
    narr/project
    narr/startup
+   narr/router
    narr/urldispatch
    narr/views
    narr/renderers
@@ -87,9 +88,10 @@ Narrative documentation in chapter form explaining how to use
    narr/security
    narr/hybrid
    narr/hooks
-   narr/advconfig
+   narr/introspector
    narr/extending
-   narr/router
+   narr/advconfig
+   narr/extconfig
    narr/threadlocals
    narr/zca
 
diff --git a/docs/latexindex.rst b/docs/latexindex.rst
index 584dd3825..4db5b64b2 100644
--- a/docs/latexindex.rst
+++ b/docs/latexindex.rst
@@ -31,6 +31,8 @@ Narrative Documentation
    narr/configuration
    narr/firstapp
    narr/project
+   narr/startup
+   narr/router
    narr/urldispatch
    narr/views
    narr/renderers
@@ -53,9 +55,10 @@ Narrative Documentation
    narr/security
    narr/hybrid
    narr/hooks
-   narr/advconfig
+   narr/introspector
    narr/extending
-   narr/startup
+   narr/advconfig
+   narr/extconfig
    narr/threadlocals
    narr/zca
 
diff --git a/docs/narr/advconfig.rst b/docs/narr/advconfig.rst
index 7b62b1a73..3a7bf2805 100644
--- a/docs/narr/advconfig.rst
+++ b/docs/narr/advconfig.rst
@@ -87,8 +87,8 @@ that ends something like this:
            Conflicting configuration actions
      For: ('view', None, '', None, <InterfaceClass pyramid.interfaces.IView>,
            None, None, None, None, None, False, None, None, None)
-    ('app.py', 14, '<module>', 'config.add_view(hello_world)')
-    ('app.py', 17, '<module>', 'config.add_view(hello_world)')
+     Line 14 of file app.py in <module>: 'config.add_view(hello_world)'
+     Line 17 of file app.py in <module>: 'config.add_view(goodbye_world)'
 
 This traceback is trying to tell us:
 
@@ -115,6 +115,8 @@ Conflict detection happens for any kind of configuration: imperative
 configuration or configuration that results from the execution of a
 :term:`scan`.
 
+.. _manually_resolving_conflicts:
+
 Manually Resolving Conflicts
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -397,76 +399,3 @@ constraints: the routes they imply require relative ordering.  Such ordering
 constraints are not absolved by two-phase configuration.  Routes are still
 added in configuration execution order.
 
-.. index::
-   single: add_directive
-   pair: configurator; adding directives
-
-.. _add_directive:
-
-Adding Methods to the Configurator via ``add_directive``
---------------------------------------------------------
-
-Framework extension writers can add arbitrary methods to a
-:term:`Configurator` by using the
-:meth:`pyramid.config.Configurator.add_directive` method of the configurator.
-This makes it possible to extend a Pyramid configurator in arbitrary ways,
-and allows it to perform application-specific tasks more succinctly.
-
-The :meth:`~pyramid.config.Configurator.add_directive` method accepts two
-positional arguments: a method name and a callable object.  The callable
-object is usually a function that takes the configurator instance as its
-first argument and accepts other arbitrary positional and keyword arguments.
-For example:
-
-.. code-block:: python
-   :linenos:
-
-   from pyramid.events import NewRequest
-   from pyramid.config import Configurator
-
-   def add_newrequest_subscriber(config, subscriber):
-       config.add_subscriber(subscriber, NewRequest).
-
-   if __name__ == '__main__':
-      config = Configurator()
-      config.add_directive('add_newrequest_subscriber',
-                           add_newrequest_subscriber)
-
-Once :meth:`~pyramid.config.Configurator.add_directive` is called, a user can
-then call the method by its given name as if it were a built-in method of the
-Configurator:
-
-.. code-block:: python
-   :linenos:
-
-   def mysubscriber(event):
-      print event.request
-
-   config.add_newrequest_subscriber(mysubscriber)
-
-A call to :meth:`~pyramid.config.Configurator.add_directive` is often
-"hidden" within an ``includeme`` function within a "frameworky" package meant
-to be included as per :ref:`including_configuration` via
-:meth:`~pyramid.config.Configurator.include`.  For example, if you put this
-code in a package named ``pyramid_subscriberhelpers``:
-
-.. code-block:: python
-   :linenos:
-
-   def includeme(config)
-      config.add_directive('add_newrequest_subscriber',
-                           add_newrequest_subscriber)
-
-The user of the add-on package ``pyramid_subscriberhelpers`` would then be
-able to install it and subsequently do:
-
-.. code-block:: python
-   :linenos:
-
-   def mysubscriber(event):
-      print event.request
-
-   from pyramid.config import Configurator
-   config = Configurator()
-   config.include('pyramid_subscriberhelpers')
-   config.add_newrequest_subscriber(mysubscriber)
diff --git a/docs/narr/extconfig.rst b/docs/narr/extconfig.rst
new file mode 100644
index 000000000..856654377
--- /dev/null
+++ b/docs/narr/extconfig.rst
@@ -0,0 +1,366 @@
+.. index::
+   single: extending configuration
+
+.. _extconfig_narr:
+
+Extending Pyramid Configuration
+===============================
+
+Pyramid allows you to extend its Configurator with custom directives.  Custom
+directives can use other directives, they can add a custom :term:`action`,
+they can participate in :term:`conflict resolution`, and they can provide
+some number of :term:`introspectable` objects.
+
+.. index::
+   single: add_directive
+   pair: configurator; adding directives
+
+.. _add_directive:
+
+Adding Methods to the Configurator via ``add_directive``
+--------------------------------------------------------
+
+Framework extension writers can add arbitrary methods to a
+:term:`Configurator` by using the
+:meth:`pyramid.config.Configurator.add_directive` method of the configurator.
+Using :meth:`~pyramid.config.Configurator.add_directive` makes it possible to
+extend a Pyramid configurator in arbitrary ways, and allows it to perform
+application-specific tasks more succinctly.
+
+The :meth:`~pyramid.config.Configurator.add_directive` method accepts two
+positional arguments: a method name and a callable object.  The callable
+object is usually a function that takes the configurator instance as its
+first argument and accepts other arbitrary positional and keyword arguments.
+For example:
+
+.. code-block:: python
+   :linenos:
+
+   from pyramid.events import NewRequest
+   from pyramid.config import Configurator
+
+   def add_newrequest_subscriber(config, subscriber):
+       config.add_subscriber(subscriber, NewRequest).
+
+   if __name__ == '__main__':
+       config = Configurator()
+       config.add_directive('add_newrequest_subscriber',
+                            add_newrequest_subscriber)
+
+Once :meth:`~pyramid.config.Configurator.add_directive` is called, a user can
+then call the added directive by its given name as if it were a built-in
+method of the Configurator:
+
+.. code-block:: python
+   :linenos:
+
+   def mysubscriber(event):
+       print event.request
+
+   config.add_newrequest_subscriber(mysubscriber)
+
+A call to :meth:`~pyramid.config.Configurator.add_directive` is often
+"hidden" within an ``includeme`` function within a "frameworky" package meant
+to be included as per :ref:`including_configuration` via
+:meth:`~pyramid.config.Configurator.include`.  For example, if you put this
+code in a package named ``pyramid_subscriberhelpers``:
+
+.. code-block:: python
+   :linenos:
+
+   def includeme(config)
+       config.add_directive('add_newrequest_subscriber',
+                            add_newrequest_subscriber)
+
+The user of the add-on package ``pyramid_subscriberhelpers`` would then be
+able to install it and subsequently do:
+
+.. code-block:: python
+   :linenos:
+
+   def mysubscriber(event):
+       print event.request
+
+   from pyramid.config import Configurator
+   config = Configurator()
+   config.include('pyramid_subscriberhelpers')
+   config.add_newrequest_subscriber(mysubscriber)
+
+Using ``config.action`` in a Directive
+--------------------------------------
+
+If a custom directive can't do its work exclusively in terms of existing
+configurator methods (such as
+:meth:`pyramid.config.Configurator.add_subscriber`, as above), the directive
+may need to make use of the :meth:`pyramid.config.Configurator.action`
+method.  This method adds an entry to the list of "actions" that Pyramid will
+attempt to process when :meth:`pyramid.config.Configurator.commit` is called.
+An action is simply a dictionary that includes a :term:`discriminator`,
+possibly a callback function, and possibly other metadata used by Pyramid's
+action system.
+
+Here's an example directive which uses the "action" method:
+
+.. code-block:: python
+   :linenos:
+
+   def add_jammyjam(config, jammyjam):
+       def register():
+           config.registry.jammyjam = jammyjam
+       config.action('jammyjam', register)
+
+   if __name__ == '__main__':
+       config = Configurator()
+       config.add_directive('add_jammyjam', add_jammyjam)
+
+Fancy, but what does it do?  The action method accepts a number of arguments.
+In the above directive named ``add_jammyjam``, we call
+:meth:`~pyramid.config.Configurator.action` with two arguments: the string
+``jammyjam`` is passed as the first argument named ``discriminator``, and the
+closure function named ``register`` is passed as the second argument named
+``callable``.
+
+When the :meth:`~pyramid.config.Configurator.action` method is called, it
+appends an action to the list of pending configuration actions.  All pending
+actions with the same discriminator value are potentially in conflict with
+one another (see :ref:`conflict_detection`).  When the
+:meth:`~pyramid.config.Configurator.commit` method of the Configurator is
+called (either explicitly or as the result of calling
+:meth:`~pyramid.config.Configurator.make_wsgi_app`), conflicting actions are
+potentially automatically resolved as per
+:ref:`automatic_conflict_resolution`.  If a conflict cannot be automatically
+resolved, a ConfigurationConflictError is raised and application startup is
+prevented.
+
+In our above example, therefore, if a consumer of our ``add_jammyjam``
+directive did this:
+
+.. code-block:: python
+   :linenos:
+
+   config.add_jammyjam('first')
+   config.add_jammyjam('second')
+
+When the action list was committed resulting from the set of calls above, our
+user's application would not start, because the discriminators of the actions
+generated by the two calls are in direct conflict.  Automatic conflict
+resolution cannot resolve the conflict (because no ``config.include`` is
+involved), and the user provided no intermediate
+:meth:`pyramid.config.Configurator.commit` call between the calls to
+``add_jammyjam`` to ensure that the successive calls did not conflict with
+each other.
+
+This demonstrates the purpose of the discriminator argument to the action
+method: it's used to indicate a uniqueness constraint for an action.  Two
+actions with the same discriminator will conflict unless the conflict is
+automatically or manually resolved. A discriminator can be any hashable
+object, but it is generally a string or a tuple.  *You use a discriminator to
+declaratively ensure that the user doesn't provide ambiguous configuration
+statements.*
+
+But let's imagine that a consumer of ``add_jammyjam`` used it in such a way
+that no configuration conflicts are generated.
+
+.. code-block:: python
+   :linenos:
+
+   config.add_jammyjam('first')
+
+What happens now?  When the ``add_jammyjam`` method is called, an action is
+appended to the pending actions list.  When the pending configuration actions
+are processed during :meth:`~pyramid.config.Configurator.commit`, and no
+conflicts occur, the *callable* provided as the second argument to the
+:meth:`~pyramid.config.Configurator.action` method within ``add_jammyjam`` is
+called with no arguments.  The callable in ``add_jammyjam`` is the
+``register`` closure function.  It simply sets the value
+``config.registry.jammyjam`` to whatever the user passed in as the
+``jammyjam`` argument to the ``add_jammyjam`` function.  Therefore, the
+result of the user's call to our directive will set the ``jammyjam``
+attribute of the registry to the string ``first``.  *A callable is used by a
+directive to defer the result of a user's call to the directive until
+conflict detection has had a chance to do its job*.
+
+Other arguments exist to the :meth:`~pyramid.config.Configurator.action`
+method, including ``args``, ``kw``, ``order``, and ``introspectables``.  
+
+``args`` and ``kw`` exist as values, which, if passed, will be used as
+arguments to the ``callable`` function when it is called back.  For example
+our directive might use them like so:
+
+.. code-block:: python
+   :linenos:
+
+   def add_jammyjam(config, jammyjam):
+       def register(*arg, **kw):
+           config.registry.jammyjam_args = arg
+           config.registry.jammyjam_kw = kw
+           config.registry.jammyjam = jammyjam
+       config.action('jammyjam', register, args=('one',), kw={'two':'two'})
+
+In the above example, when this directive is used to generate an action, and
+that action is committed, ``config.registry.jammyjam_args`` will be set to
+``('one',)`` and ``config.registry.jammyjam_kw`` will be set to
+``{'two':'two'}``.  ``args`` and ``kw`` are honestly not very useful when
+your ``callable`` is a closure function, because you already usually have
+access to every local in the directive without needing them to be passed
+back.  They can be useful, however, if you don't use a closure as a callable.
+
+``order`` is a crude order control mechanism.  ``order`` defaults to the
+integer ``0``; it can be set to any other integer.  All actions that share an
+order will be called before other actions that share a higher order.  This
+makes it possible to write a directive with callable logic that relies on the
+execution of the callable of another directive being done first.  For
+example, Pyramid's :meth:`pyramid.config.Configurator.add_view` directive
+registers an action with a higher order than the
+:meth:`pyramid.config.Configurator.add_route` method.  Due to this, the
+``add_view`` method's callable can assume that, if a ``route_name`` was
+passed to it, that a route by this name was already registered by
+``add_route``, and if such a route has not already been registered, it's a
+configuration error (a view that names a nonexistent route via its
+``route_name`` parameter will never be called).
+
+``introspectables`` is a sequence of :term:`introspectable` objects.  You can
+pass a sequence of introspectables to the
+:meth:`~pyramid.config.Configurator.action` method, which allows you to
+augment Pyramid's configuration introspection system.
+
+.. _introspection:
+
+Configuration Introspection
+---------------------------
+
+.. warning::
+
+   The introspection subsystem is new in Pyramid 1.3.
+
+Pyramid provides a configuration introspection system that can be used by
+debugging tools to provide visibility into the configuration of a running
+application.
+
+All built-in Pyramid directives (such as
+:meth:`pyramid.config.Configurator.add_view` and
+:meth:`pyramid.config.Configurator.add_route`) register a set of
+introspectables when called.  For example, when you register a view via
+``add_view``, the directive registers at least one introspectable: an
+introspectable about the view registration itself, providing human-consumable
+values for the arguments it was passed.  You can later use the introspection
+query system to determine whether a particular view uses a renderer, or
+whether a particular view is limited to a particular request method, or which
+routes a particular view is registered against.  The Pyramid "debug toolbar"
+makes use of the introspection system in various ways to display information
+to Pyramid developers.
+
+Introspection values are set when a sequence of :term:`introspectable`
+objects is passed to the :meth:`~pyramid.config.Configurator.action` method.
+Here's an example of a directive which uses introspectables:
+
+.. code-block:: python
+   :linenos:
+
+   def add_jammyjam(config, value):
+       def register():
+           config.registry.jammyjam = value
+       intr = config.introspectable(category_name='jammyjams', 
+                                    discriminator='jammyjam',
+                                    title='a jammyjam',
+                                    type_name=None)
+       intr['value'] = value
+       config.action('jammyjam', register, introspectables=(intr,))
+
+   if __name__ == '__main__':
+       config = Configurator()
+       config.add_directive('add_jammyjam', add_jammyjam)
+
+If you notice, the above directive uses the ``introspectable`` attribute of a
+Configurator (:attr:`pyramid.config.Configurator.introspectable`) to create
+an introspectable object.  The introspectable object's constructor requires
+at least four arguments: the ``category_name``, the ``discriminator``, the
+``title``, and the ``type_name``.
+
+The ``category_name`` is a string representing the logical category for this
+introspectable.  Usually the category_name is a pluralization of the type of
+object being added via the action.
+
+The ``discriminator`` is a value unique **within the category** (unlike the
+action discriminator, which must be unique within the entire set of actions).
+It is typically a string or tuple representing the values unique to this
+introspectable within the category.  It is used to generate links and as part
+of a relationship-forming target for other introspectables.
+
+The ``title`` is a human-consumable string that can be used by introspection
+system frontends to show a friendly summary of this introspectable.
+
+The ``type_name`` is a value that can be used to subtype this introspectable
+within its category for for sorting and presentation purposes.  It can be any
+value.
+
+An introspectable is also dictionary-like.  It can contain any set of
+key/value pairs, typically related to the arguments passed to its related
+directive.  While the category_name, discriminator, title and type_name are
+*metadata* about the introspectable, the values provided as key/value pairs
+are the actual data provided by the introspectable.  In the above example, we
+set the ``value`` key to the value of the ``value`` argument passed to the
+directive.
+
+Our directive above mutates the introspectable, and passes it in to the
+``action`` method as the first element of a tuple as the value of the
+``introspectable`` keyword argument.  This associates this introspectable
+with the action.  Introspection tools will then display this introspectable
+in their index.
+
+Introspectable Relationships
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Two introspectables may have relationships between each other.
+
+.. code-block:: python
+   :linenos:
+
+   def add_jammyjam(config, value, template):
+       def register():
+           config.registry.jammyjam = (value, template)
+       intr = config.introspectable(category_name='jammyjams', 
+                                    discriminator='jammyjam',
+                                    title='a jammyjam',
+                                    type_name=None)
+       intr['value'] = value
+       tmpl_intr = config.introspectable(category_name='jammyjam templates',
+                                         discriminator=template,
+                                         title=template,
+                                         type_name=None)
+       tmpl_intr['value'] = template
+       intr.relate('jammyjam templates', template)
+       config.action('jammyjam', register, introspectables=(intr, tmpl_intr))
+
+   if __name__ == '__main__':
+       config = Configurator()
+       config.add_directive('add_jammyjam', add_jammyjam)
+
+In the above example, the ``add_jammyjam`` directive registers two
+introspectables.  The first is related to the ``value`` passed to the
+directive; the second is related to the ``template`` passed to the directive.
+If you believe a concept within a directive is important enough to have its
+own introspectable, you can cause the same directive to register more than
+one introspectable, registering one introspectable for the "main idea" and
+another for a related concept.
+
+The call to ``intr.relate`` above
+(:meth:`pyramid.interfaces.IIntrospectable.relate`) is passed two arguments:
+a category name and a directive.  The example above effectively indicates
+that the directive wishes to form a relationship between the ``intr``
+introspectable and the ``tmpl_intr`` introspectable; the arguments passed to
+``relate`` are the category name and discriminator of the ``tmpl_intr``
+introspectable.
+
+Relationships need not be made between two introspectables created by the
+same directive.  Instead, a relationship can be formed between an
+introspectable created in one directive and another introspectable created in
+another by calling ``relate`` on either side with the other directive's
+category name and discriminator.  An error will be raised at configuration
+commit time if you attempt to relate an introspectable with another
+nonexistent introspectable, however.
+
+Introspectable relationships will show up in frontend system renderings of
+introspection values.  For example, if a view registration names a route
+name, the introspectable related to the view callable will show a reference
+to the route to which it relates to and vice versa.
diff --git a/docs/narr/introspector.rst b/docs/narr/introspector.rst
new file mode 100644
index 000000000..cfc6144dd
--- /dev/null
+++ b/docs/narr/introspector.rst
@@ -0,0 +1,542 @@
+.. index::
+   single: introspection
+   single: introspector
+
+.. _using_introspection:
+
+Pyramid Configuration Introspection
+===================================
+
+When Pyramid starts up, each call to a :term:`configuration directive` causes
+one or more :term:`introspectable` objects to be registered with an
+:term:`introspector`.  The introspector can be queried by application code to
+obtain information about the configuration of the running application.  This
+feature is useful for debug toolbars, command-line scripts which show some
+aspect of configuration, and for runtime reporting of startup-time
+configuration settings.
+
+.. warning::
+
+   Introspection is new in Pyramid 1.3.
+
+Using the Introspector
+----------------------
+
+Here's an example of using Pyramid's introspector from within a view
+callable:
+
+.. code-block:: python
+   :linenos:
+
+    from pyramid.view import view_config
+    from pyramid.response import Response
+
+    @view_config(route_name='bar')
+    def route_accepts(request):
+        introspector = request.registry.introspector
+        route_name = request.matched_route.name
+        route_intr = introspector.get('routes', route_name)
+        return Response(str(route_intr['pattern']))
+
+This view will return a response that contains the "pattern" argument
+provided to the ``add_route`` method of the route which matched when the view
+was called.  It uses the :meth:`pyramid.interfaces.IIntrospector.get` method
+to return an introspectable in the category ``routes`` with a
+:term:`discriminator` equal to the matched route name.  It then uses the
+returned introspectable to obtain an "pattern" value.
+
+The introspectable returned by the query methods of the introspector has
+methods and attributes described by
+:class:`pyramid.interfaces.IIntrospectable`.  In particular, the
+:meth:`~pyramid.interfaces.IIntrospector.get`,
+:meth:`~pyramid.interfaces.IIntrospector.get_category`,
+:meth:`~pyramid.interfaces.IIntrospector.categories`,
+:meth:`~pyramid.interfaces.IIntrospector.categorized`, and
+:meth:`~pyramid.interfaces.IIntrospector.related` methods of an introspector
+can be used to query for introspectables.
+
+Introspectable Objects
+----------------------
+
+Introspectable objects are returned from query methods of an introspector.
+Each introspectable object implements the attributes and methods the
+documented at :class:`pyramid.interfaces.IIntrospectable`.
+
+The important attributes shared by all introspectables are the following:
+
+``title``
+
+  A human-readable text title describing the introspectable
+
+``category_name``
+
+  A text category name describing the introspection category to which this
+  introspectable belongs.  It is often a plural if there are expected to be
+  more than one introspectable registered within the category.
+
+``discriminator``
+
+  A hashable object representing the unique value of this introspectable
+  within its category.
+
+``discriminator_hash``
+
+  The integer hash of the discriminator (useful for using in HTML links).
+
+``type_name``
+
+  The text name of a subtype within this introspectable's category.  If there
+  is only one type name in this introspectable's category, this value will
+  often be a singular version of the category name but it can be an arbitrary
+  value.
+
+``action_info``
+
+  An object describing the directive call site which caused this
+  introspectable to be registered; contains attributes described in
+  :class:`pyramid.interfaces.IActionInfo`.
+
+Besides having the attributes described above, an introspectable is a
+dictionary-like object.  An introspectable can be queried for data values via
+its ``__getitem__``, ``get``, ``keys``, ``values``, or ``items`` methods.
+For example:
+
+.. code-block:: python
+   :linenos:
+
+    route_intr = introspector.get('routes', 'edit_user')
+    pattern = route_intr['pattern']
+
+Pyramid Introspection Categories
+--------------------------------
+
+The list of concrete introspection categories provided by built-in Pyramid
+configuration directives follows.  Add-on packages may supply other
+introspectables in categories not described here.
+
+``subscribers``
+
+  Each introspectable in the ``subscribers`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_subscriber` (or the decorator
+  equivalent); each will have the following data.
+
+  ``subscriber``
+
+    The subscriber callable object (the resolution of the ``subscriber``
+    argument passed to ``add_susbcriber``).
+
+  ``interfaces``
+
+    A sequence of interfaces (or classes) that are subscribed to (the
+    resolution of the ``ifaces`` argument passed to ``add_subscriber``).
+
+``response adapters``
+
+  Each introspectable in the ``response adapters`` category represents a call
+  to :meth:`pyramid.config.Configurator.add_response_adapter` (or a decorator
+  equivalent); each will have the following data.
+
+  ``adapter``
+
+    The adapter object (the resolved ``adapter`` argument to
+    ``add_response_adapter``).
+
+  ``type``
+
+    The resolved ``type_or_iface`` argument passed to
+    ``add_response_adapter``.
+
+``root factories``
+
+  Each introspectable in the ``root factories`` category represents a call to
+  :meth:`pyramid.config.Configurator.set_root_factory` (or the Configurator
+  constructor equivalent) *or* a ``factory`` argument passed to
+  :meth:`pyramid.config.Configurator.add_route`; each will have the following
+  data.
+
+  ``factory``
+
+    The factory object (the resolved ``factory`` argument to
+    ``set_root_factory``).
+
+  ``route_name``
+
+    The name of the route which will use this factory.  If this is the
+    *default* root factory (if it's registered during a call to
+    ``set_root_factory``), this value will be ``None``.
+
+``session factory``
+
+  Only one introspectable will exist in the ``session factory`` category.  It
+  represents a call to :meth:`pyramid.config.Configurator.set_session_factory`
+  (or the Configurator constructor equivalent); it will have the following
+  data.
+
+  ``factory``
+
+    The factory object (the resolved ``factory`` argument to
+    ``set_session_factory``).
+
+``request factory``
+
+  Only one introspectable will exist in the ``request factory`` category.  It
+  represents a call to :meth:`pyramid.config.Configurator.set_request_factory`
+  (or the Configurator constructor equivalent); it will have the following
+  data.
+
+  ``factory``
+
+    The factory object (the resolved ``factory`` argument to
+    ``set_request_factory``).
+
+``locale negotiator``
+
+  Only one introspectable will exist in the ``locale negotiator`` category.
+  It represents a call to
+  :meth:`pyramid.config.Configurator.set_locale_negotiator` (or the
+  Configurator constructor equivalent); it will have the following data.
+
+  ``negotiator``
+
+    The factory object (the resolved ``negotiator`` argument to
+    ``set_locale_negotiator``).
+
+``renderer factories``
+
+  Each introspectable in the ``renderer factories`` category represents a
+  call to :meth:`pyramid.config.Configurator.add_renderer` (or the
+  Configurator constructor equivalent); each will have the following data.
+
+  ``name``
+
+    The name of the renderer (the value of the ``name`` argument to
+    ``add_renderer``).
+
+  ``factory``
+
+    The factory object (the resolved ``factory`` argument to
+    ``add_renderer``).
+
+``renderer globals factory``
+
+  There will be one and only one introspectable in the ``renderer globals
+  factory`` category.  It represents a call to
+  :meth:`pyramid.config.Configurator.set_renderer_globals_factory`; it will
+  have the following data.
+
+  ``factory``
+
+    The factory object (the resolved ``factory`` argument to
+    ``set_renderer_globals_factory``).
+
+``routes``
+
+  Each introspectable in the ``routes`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_route`; each will have the following
+  data.
+
+  ``name``
+
+    The ``name`` argument passed to ``add_route``.
+
+  ``pattern``
+
+    The ``pattern`` argument passed to ``add_route``.
+
+  ``factory``
+
+    The (resolved) ``factory`` argument passed to ``add_route``.
+
+  ``xhr``
+
+    The ``xhr`` argument passed to ``add_route``.
+
+  ``request_method``
+
+    The ``request_method`` argument passed to ``add_route``.
+
+  ``request_methods``
+
+    A sequence of request method names implied by the ``request_method``
+    argument passed to ``add_route`` or the value ``None`` if a
+    ``request_method`` argument was not supplied.
+
+  ``path_info``
+
+    The ``path_info`` argument passed to ``add_route``.
+
+  ``request_param``
+
+    The ``request_param`` argument passed to ``add_route``.
+
+  ``header``
+
+    The ``header`` argument passed to ``add_route``.
+
+  ``accept``
+
+    The ``accept`` argument passed to ``add_route``.
+
+  ``traverse``
+
+    The ``traverse`` argument passed to ``add_route``.
+
+  ``custom_predicates``
+
+    The ``custom_predicates`` argument passed to ``add_route``.
+
+  ``pregenerator``
+
+    The ``pregenerator`` argument passed to ``add_route``.
+
+  ``pregenerator``
+
+    The ``static`` argument passed to ``add_route``.
+
+  ``pregenerator``
+
+    The ``use_global_views`` argument passed to ``add_route``.
+
+  ``object``
+
+     The :class:`pyramid.interfaces.IRoute` object that is used to perform
+     matching and generation for this route.
+
+``authentication policy``
+
+  There will be one and only one introspectable in the ``authentication
+  policy`` category.  It represents a call to the
+  :meth:`pyramid.config.Configurator.set_authentication_policy` method (or
+  its Configurator constructor equivalent); it will have the following data.
+
+  ``policy``
+
+    The policy object (the resolved ``policy`` argument to
+    ``set_authentication_policy``).
+
+``authorization policy``
+
+  There will be one and only one introspectable in the ``authorization
+  policy`` category.  It represents a call to the
+  :meth:`pyramid.config.Configurator.set_authorization_policy` method (or its
+  Configurator constructor equivalent); it will have the following data.
+
+  ``policy``
+
+    The policy object (the resolved ``policy`` argument to
+    ``set_authorization_policy``).
+
+``default permission``
+
+  There will be one and only one introspectable in the ``default permission``
+  category.  It represents a call to the
+  :meth:`pyramid.config.Configurator.set_default_permission` method (or its
+  Configurator constructor equivalent); it will have the following data.
+
+  ``value``
+
+    The permission name passed to ``set_default_permission``.
+
+``views``
+
+  Each introspectable in the ``views`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_view`; each will have the following
+  data.
+
+  ``name``
+
+    The ``name`` argument passed to ``add_view``.
+
+  ``context``
+
+    The (resolved) ``context`` argument passed to ``add_view``.
+
+  ``containment``
+
+    The (resolved) ``containment`` argument passed to ``add_view``.
+
+  ``request_param``
+
+    The ``request_param`` argument passed to ``add_view``.
+
+  ``request_methods``
+
+    A sequence of request method names implied by the ``request_method``
+    argument passed to ``add_view`` or the value ``None`` if a
+    ``request_method`` argument was not supplied.
+
+  ``route_name``
+
+    The ``route_name`` argument passed to ``add_view``.
+
+  ``attr``
+
+    The ``attr`` argument passed to ``add_view``.
+
+  ``xhr``
+
+    The ``xhr`` argument passed to ``add_view``.
+
+  ``accept``
+
+    The ``accept`` argument passed to ``add_view``.
+
+  ``header``
+
+    The ``header`` argument passed to ``add_view``.
+
+  ``path_info``
+
+    The ``path_info`` argument passed to ``add_view``.
+
+  ``match_param``
+
+    The ``match_param`` argument passed to ``add_view``.
+
+  ``callable``
+
+    The (resolved) ``view`` argument passed to ``add_view``.  Represents the
+    "raw" view callable.
+
+  ``derived_callable``
+
+    The view callable derived from the ``view`` argument passed to
+    ``add_view``.  Represents the view callable which Pyramid itself calls
+    (wrapped in security and other wrappers).
+
+  ``mapper``
+
+    The (resolved) ``mapper`` argument passed to ``add_view``.
+
+  ``decorator``
+
+    The (resolved) ``decorator`` argument passed to ``add_view``.
+
+``permissions``
+
+  Each introspectable in the ``permissions`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_view` that has an explicit
+  ``permission`` argument to *or* a call to
+  :meth:`pyramid.config.Configurator.set_default_permission`; each will have
+  the following data.
+
+  ``value``
+
+    The permission name passed to ``add_view`` or ``set_default_permission``.
+
+``templates``
+
+  Each introspectable in the ``templates`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_view` that has a ``renderer``
+  argument which points to a template; each will have the following data.
+
+  ``name``
+
+    The renderer's name (a string).
+
+  ``type``
+
+    The renderer's type (a string).
+
+  ``renderer``
+
+    The :class:`pyramid.interfaces.IRendererInfo` object which represents
+    this template's renderer.
+
+``view mapper``
+
+  Each introspectable in the ``permissions`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_view` that has an explicit
+  ``mapper`` argument to *or* a call to
+  :meth:`pyramid.config.Configurator.set_view_mapper`; each will have
+  the following data.
+
+  ``mapper``
+
+    The (resolved) ``mapper`` argument passed to ``add_view`` or
+    ``set_view_mapper``.
+
+``asset overrides``
+
+  Each introspectable in the ``asset overrides`` category represents a call
+  to :meth:`pyramid.config.Configurator.override_asset`; each will have the
+  following data.
+
+  ``to_override``
+
+    The ``to_override`` argument (an asset spec) passed to
+    ``override_asset``.
+
+  ``override_with``
+
+    The ``override_with`` argument (an asset spec) passed to
+    ``override_asset``.
+
+``translation directories``
+
+  Each introspectable in the ``asset overrides`` category represents an
+  individual element in a ``specs`` argument passed to to
+  :meth:`pyramid.config.Configurator.add_translation_dirs`; each will have
+  the following data.
+
+  ``directory``
+
+    The absolute path of the translation directory.
+
+  ``spec``
+
+    The asset specification passed to ``add_translation_dirs``.
+
+``tweens``
+
+  Each introspectable in the ``tweens`` category represents a call to
+  :meth:`pyramid.config.Configurator.add_tween`; each will have the following
+  data.
+
+  ``name``
+
+    The dotted name to the tween factory as a string (passed as
+    the ``tween_factory`` argument to ``add_tween``).
+
+  ``factory``
+
+    The (resolved) tween factory object.
+
+  ``type``
+
+    ``implict`` or ``explicit`` as a string.
+
+  ``under``
+
+     The ``under`` argument passed to ``add_tween`` (a string).
+
+  ``over``
+
+     The ``over`` argument passed to ``add_tween`` (a string).
+
+Introspection in the Toolbar
+----------------------------
+
+The Pyramid debug toolbar (part of the ``pyramid_debugtoolbar`` package)
+provides a canned view of all registered introspectables and their
+relationships.  It looks something like this:
+
+.. image:: tb_introspector.png
+
+Disabling Introspection
+-----------------------
+
+You can disable Pyramid introspection by passing the object
+:attr:`pyramid.registry.noop_introspector` to the :term:`Configurator`
+constructor in your application setup:
+
+.. code-block:: python
+
+   from pyramid.config import Configurator
+   from pyramid.registry import noop_introspector
+   config = Configurator(..., introspector=noop_introspector)
+
+When the noop introspector is active, all introspectables generated by
+configuration directives are thrown away.  A noop introspector behaves just
+like a "real" introspector, but the methods of a noop introspector do nothing
+and return null values.
diff --git a/docs/narr/tb_introspector.png b/docs/narr/tb_introspector.png
new file mode 100644
index 000000000..231a094f7
--- /dev/null
+++ b/docs/narr/tb_introspector.png