Add Configurator context manager 'route_prefix_context' to allow for adding routes and including configuration callables with a particular route prefix.

4 files changed, 149 insertions, 29 deletions

diff --git a/docs/narr/urldispatch.rst b/docs/narr/urldispatch.rst
index 9ac01e24a..00c7bd3bf 100644
--- a/docs/narr/urldispatch.rst
+++ b/docs/narr/urldispatch.rst
@@ -1045,6 +1045,24 @@ may be added in the future.  For example:
        config = Configurator()
        config.include(users_include, route_prefix='/users')
 
+A convenience context manager exists to set the route prefix for any
+:meth:`pyramid.config.Configurator.add_route` or
+:meth:`pyramid.config.Configurator.include` calls within the context.
+
+.. code-block:: python
+   :linenos:
+
+   from pyramid.config import Configurator
+
+   def timing_include(config):
+      config.add_route('timing.show_times', '/times')
+
+   def main(global_config, **settings)
+      config = Configurator()
+      with config.route_prefix_context('/timing'):
+         config.include(timing_include)
+         config.add_route('timing.average', '/average')
+
 .. index::
    single: route predicates (custom)
 
diff --git a/pyramid/config/__init__.py b/pyramid/config/__init__.py
index a34f0b4db..886eec0df 100644
--- a/pyramid/config/__init__.py
+++ b/pyramid/config/__init__.py
@@ -790,21 +790,6 @@ class Configurator(
 
         action_state = self.action_state
 
-        if route_prefix is None:
-            route_prefix = ''
-
-        old_route_prefix = self.route_prefix
-        if old_route_prefix is None:
-            old_route_prefix = ''
-
-        route_prefix = '%s/%s' % (
-            old_route_prefix.rstrip('/'),
-            route_prefix.lstrip('/')
-            )
-        route_prefix = route_prefix.strip('/')
-        if not route_prefix:
-            route_prefix = None
-
         c = self.maybe_dotted(callable)
         module = self.inspect.getmodule(c)
         if module is c:
@@ -825,20 +810,22 @@ class Configurator(
             
 
         if action_state.processSpec(spec):
-            configurator = self.__class__(
-                registry=self.registry,
-                package=package_of(module),
-                root_package=self.root_package,
-                autocommit=self.autocommit,
-                route_prefix=route_prefix,
-                )
-            configurator.basepath = os.path.dirname(sourcefile)
-            configurator.includepath = self.includepath + (spec,)
-            self.begin()
-            try:
-                c(configurator)
-            finally:
-                self.end()
+            with self.route_prefix_context(route_prefix):
+                configurator = self.__class__(
+                    registry=self.registry,
+                    package=package_of(module),
+                    root_package=self.root_package,
+                    autocommit=self.autocommit,
+                    route_prefix=self.route_prefix,
+                    )
+                configurator.basepath = os.path.dirname(sourcefile)
+                configurator.includepath = self.includepath + (spec,)
+
+                self.begin()
+                try:
+                    c(configurator)
+                finally:
+                    self.end()
 
     def add_directive(self, name, directive, action_wrap=True):
         """
diff --git a/pyramid/config/routes.py b/pyramid/config/routes.py
index 203baa128..a83b424b6 100644
--- a/pyramid/config/routes.py
+++ b/pyramid/config/routes.py
@@ -1,3 +1,4 @@
+import contextlib
 import warnings
 
 from pyramid.compat import urlparse
@@ -467,3 +468,53 @@ class RoutesConfiguratorMixin(object):
             self.registry.registerUtility(mapper, IRoutesMapper)
         return mapper
 
+    @contextlib.contextmanager
+    def route_prefix_context(self, route_prefix):
+        """ Return this configurator with the
+        :attr:`pyramid.config.Configurator.route_prefix` attribute mutated to
+        include the new ``route_prefix``.
+
+        When the context exits, the ``route_prefix`` is reset to the original.
+
+        Example Usage:
+
+        >>> config = Configurator()
+        >>> with config.route_prefix_context('foo'):
+        ...     config.add_route('bar', '/bar')
+
+        Arguments
+
+        route_prefix
+
+          A string suitable to be used as a route prefix, or ``None``.
+
+        .. versionadded:: 1.9.10
+        """
+
+        original_route_prefix = self.route_prefix
+
+        if route_prefix is None:
+            route_prefix = ''
+
+        old_route_prefix = self.route_prefix
+        if old_route_prefix is None:
+            old_route_prefix = ''
+
+        route_prefix = '{}/{}'.format(
+            old_route_prefix.rstrip('/'),
+            route_prefix.lstrip('/'),
+        )
+
+        route_prefix = route_prefix.strip('/')
+
+        if not route_prefix:
+            route_prefix = None
+
+        self.begin()
+        try:
+            self.route_prefix = route_prefix
+            yield
+
+        finally:
+            self.route_prefix = original_route_prefix
+            self.end()
diff --git a/pyramid/tests/test_url.py b/pyramid/tests/test_url.py
index af2e5405c..31b3dd571 100644
--- a/pyramid/tests/test_url.py
+++ b/pyramid/tests/test_url.py
@@ -1251,6 +1251,70 @@ class Test_external_static_url_integration(unittest.TestCase):
             request.route_url('acme', foo='bar'),
             'http://acme.org/bar')
 
+class Test_with_route_prefix(unittest.TestCase):
+
+    def setUp(self):
+        self.config = testing.setUp()
+
+    def tearDown(self):
+        testing.tearDown()
+
+    def _makeRequest(self, route):
+        from pyramid.request import Request
+        return Request.blank(route)
+
+    def test_old_route_is_preserved(self):
+        self.config.route_prefix = 'old_prefix'
+        with self.config.route_prefix_context('new_addon'):
+            assert 'new_addon' in self.config.route_prefix
+
+        assert 'old_prefix' == self.config.route_prefix
+
+    def test_route_prefix_none(self):
+        self.config.route_prefix = 'old_prefix'
+        with self.config.route_prefix_context(None):
+            assert 'old_prefix' == self.config.route_prefix
+
+        assert 'old_prefix' == self.config.route_prefix
+
+    def test_route_prefix_empty(self):
+        self.config.route_prefix = 'old_prefix'
+        with self.config.route_prefix_context(''):
+            assert 'old_prefix' == self.config.route_prefix
+
+        assert 'old_prefix' == self.config.route_prefix
+
+    def test_route_has_prefix(self):
+        with self.config.route_prefix_context('bar'):
+            self.config.add_route('acme', '/foo')
+        request = self._makeRequest('/')
+        self.assertEqual(
+            request.route_url('acme'),
+            'http://localhost/bar/foo',
+        )
+
+    def test_route_does_not_have_prefix(self):
+        with self.config.route_prefix_context('bar'):
+            pass
+
+        self.config.add_route('acme', '/foo')
+        request = self._makeRequest('/')
+        self.assertEqual(
+            request.route_url('acme'),
+            'http://localhost/foo',
+        )
+
+    def test_error_reset_prefix(self):
+        self.config.route_prefix = 'old_prefix'
+
+        try:
+            with self.config.route_prefix_context('new_prefix'):
+                raise RuntimeError
+        except RuntimeError:
+            pass
+
+        assert self.config.route_prefix == 'old_prefix'
+
 class DummyContext(object):
     def __init__(self, next=None):
         self.next = next