use inherit_slash=True on add_route to opt-in to no trailing slash

2 files changed, 36 insertions, 7 deletions

diff --git a/src/pyramid/config/__init__.py b/src/pyramid/config/__init__.py
index 00c3e6a02..475f0d9a2 100644
--- a/src/pyramid/config/__init__.py
+++ b/src/pyramid/config/__init__.py
@@ -602,7 +602,9 @@ class Configurator(
         configuration conflict by registering something with the same
         configuration parameters.
 
-        If the ``route_prefix`` is supplied, it must be a string.  Any calls
+        If the ``route_prefix`` is supplied, it must be a string and will
+        have a similar effect to using
+        :meth:`pyramid.config.Configurator.route_prefix_context`.  Any calls
         to :meth:`pyramid.config.Configurator.add_route` within the included
         callable will have their pattern prefixed with the value of
         ``route_prefix``. This can be used to help mount a set of routes at a
diff --git a/src/pyramid/config/routes.py b/src/pyramid/config/routes.py
index 7bddf4e67..e7e981df0 100644
--- a/src/pyramid/config/routes.py
+++ b/src/pyramid/config/routes.py
@@ -40,6 +40,7 @@ class RoutesConfiguratorMixin(object):
         path=None,
         pregenerator=None,
         static=False,
+        inherit_slash=None,
         **predicates
     ):
         """ Add a :term:`route configuration` to the current
@@ -139,6 +140,26 @@ class RoutesConfiguratorMixin(object):
 
           .. versionadded:: 1.1
 
+        inherit_slash
+
+          This argument can only be used when the ``pattern`` is an empty
+          string (``''``). By default, the composed route pattern will always
+          includes a trailing slash, but this argument provides a way to
+          opt-out if both, you and the integrator (the developer setting the
+          :term:`route prefix`), agree that the pattern should not contain
+          a trailing slash. For example:
+
+          .. code-block:: python
+
+              with config.route_prefix_context('/users'):
+                  config.add_route('users', '', inherit_slash=True)
+
+          In this example, the resulting route pattern will be ``/users``.
+          Alternatively, if the route prefix were ``/users/`` then the
+          resulting route pattern would be ``/users/``.
+
+          .. versionadded:: 2.0
+
         Predicate Arguments
 
         pattern
@@ -329,6 +350,11 @@ class RoutesConfiguratorMixin(object):
         if pattern is None:
             raise ConfigurationError('"pattern" argument may not be None')
 
+        if inherit_slash and pattern != '':
+            raise ConfigurationError(
+                '"inherit_slash" may only be used with an empty pattern'
+            )
+
         # check for an external route; an external route is one which is
         # is a full url (e.g. 'http://example.com/{id}')
         parsed = urlparse.urlparse(pattern)
@@ -364,10 +390,12 @@ class RoutesConfiguratorMixin(object):
             static = True
 
         elif self.route_prefix:
-            if pattern == '':
-                pattern = self.route_prefix.rstrip('/')
+            if pattern == '' and inherit_slash:
+                pattern = self.route_prefix
             else:
-                pattern = self.route_prefix.rstrip('/') + '/' + pattern.lstrip('/')
+                pattern = (
+                    self.route_prefix.rstrip('/') + '/' + pattern.lstrip('/')
+                )
 
         mapper = self.get_routes_mapper()
 
@@ -517,9 +545,8 @@ class RoutesConfiguratorMixin(object):
 
     @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``.
+        """
+        Return this configurator with a :term:`route prefix` temporarily set.
 
         When the context exits, the ``route_prefix`` is reset to the original.