Replace simplegeneric with singledispatch (PEP 443).

Closes-Bug: #1226813
Change-Id: I1ba149ac00353460065d4cddbe3ccd8782aaa611

5 files changed, 39 insertions, 18 deletions

diff --git a/docs/source/jsonify.rst b/docs/source/jsonify.rst
index ac06c30..b5c6053 100644
--- a/docs/source/jsonify.rst
+++ b/docs/source/jsonify.rst
@@ -9,9 +9,7 @@ JSON. To get started, create a file in your project called
 ``json.py`` and import it in your project's ``app.py``.
 
 Your ``json`` module will contain a series of rules for generating
-JSON from objects you return in your controller, utilizing
-"generic" function support from the 
-`simplegeneric <http://pypi.python.org/pypi/simplegeneric>`_ library.
+JSON from objects you return in your controller.
 
 Let's say that we have a controller in our Pecan application which
 we want to use to return JSON output for a :class:`User` object::
@@ -35,7 +33,7 @@ rule in your ``json.py``::
     from pecan.jsonify import jsonify
     from myproject import model
     
-    @jsonify.when_type(model.User)
+    @jsonify.register(model.User)
     def jsonify_user(user):
         return dict(
             name = user.name,
diff --git a/pecan/decorators.py b/pecan/decorators.py
index 2938fc1..f40d16a 100644
--- a/pecan/decorators.py
+++ b/pecan/decorators.py
@@ -33,9 +33,10 @@ def expose(template=None,
                      directory.
     :param content_type: The content-type to use for this template.
     :param generic: A boolean which flags this as a "generic" controller,
-                    which uses generic functions based upon ``simplegeneric``
-                    generic functions.  Allows you to split a single
-                    controller into multiple paths based upon HTTP method.
+                    which uses generic functions based upon
+                    ``functools.singledispatch`` generic functions.  Allows you
+                    to split a single controller into multiple paths based upon
+                    HTTP method.
     '''
 
     if template == 'json':
diff --git a/pecan/jsonify.py b/pecan/jsonify.py
index 2d89c53..726213a 100644
--- a/pecan/jsonify.py
+++ b/pecan/jsonify.py
@@ -17,18 +17,24 @@ except ImportError:  # pragma no cover
     webob_dicts = (MultiDict,)
 
 import six
-from simplegeneric import generic
+try:
+    from functools import singledispatch
+except ImportError:  # pragma: no cover
+    from singledispatch import singledispatch
 
 try:
-    from sqlalchemy.engine.base import ResultProxy, RowProxy
+    from sqlalchemy.engine.result import ResultProxy, RowProxy
 except ImportError:  # pragma no cover
-    # dummy classes since we don't have SQLAlchemy installed
+    try:
+        from sqlalchemy.engine.base import ResultProxy, RowProxy
+    except ImportError:  # pragma no cover
+        # dummy classes since we don't have SQLAlchemy installed
 
-    class ResultProxy:  # noqa
-        pass
+        class ResultProxy(object):  # noqa
+            pass
 
-    class RowProxy:  # noqa
-        pass
+        class RowProxy(object):  # noqa
+            pass
 
 
 #
@@ -105,11 +111,17 @@ class GenericJSON(JSONEncoder):
         else:
             return JSONEncoder.default(self, obj)
 
-
 _default = GenericJSON()
 
 
-@generic
+def with_when_type(f):
+    # Add some backwards support for simplegeneric's API
+    f.when_type = f.register
+    return f
+
+
+@with_when_type
+@singledispatch
 def jsonify(obj):
     return _default.default(obj)
 
diff --git a/requirements.txt b/requirements.txt
index 5146301..9205775 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,4 @@
 WebOb>=1.2dev
 Mako>=0.4.0
 WebTest>=1.3.1
-simplegeneric>=0.8.1
 six
diff --git a/setup.py b/setup.py
index efb3454..2d724f6 100644
--- a/setup.py
+++ b/setup.py
@@ -39,10 +39,21 @@ except:
     #
     requirements.append('argparse')
 
+try:
+    from functools import singledispatch  # noqa
+except:
+    #
+    # This was introduced in Python 3.4 - the singledispatch package contains
+    # a backported replacement for 2.6 through 3.3
+    #
+    requirements.append('singledispatch')
+
+
 tests_require = requirements + [
     'virtualenv',
     'gunicorn',
-    'mock'
+    'mock',
+    'sqlalchemy'
 ]
 if sys.version_info < (2, 7):
     tests_require += ['unittest2']