Replace the use of pkg_resources with the importlib library.

Change-Id: Iafb96d53196ff74c98f2fbc7caf2eb8fbdc70029

Author: CaselIT

doc/build/caching.rst

@@ -284,7 +284,7 @@ using a :class:`.CacheImpl` subclass.    This class implements
 the rudimental methods Mako needs to implement the caching
 API.   Mako includes the :class:`.BeakerCacheImpl` class to
 provide the default implementation.  A :class:`.CacheImpl` class
-is acquired by Mako using a ``pkg_resources`` entrypoint, using
+is acquired by Mako using a ``importlib.metatada`` entrypoint, using
 the name given as the ``cache_impl`` argument to :class:`.Template`
 or :class:`.TemplateLookup`.    This entry point can be
 installed via the standard `setuptools`/``setup()`` procedure, underneath

doc/build/unreleased/pgk_resources.rst

@@ -0,0 +1,5 @@
+.. change::
+    :tags: setup
+
+    Replaced the use of ``pkg_resources`` with the ``importlib`` library.
+    For Python < 3.8 the library ``importlib_metadata`` is used.

mako/compat.py

@@ -11,6 +11,7 @@
 
 win32 = sys.platform.startswith("win")
 pypy = hasattr(sys, "pypy_version_info")
+py38 = sys.version_info >= (3, 8)
 
 ArgSpec = collections.namedtuple(
     "ArgSpec", ["args", "varargs", "keywords", "defaults"]
@@ -59,3 +60,17 @@ def exception_as():
 
 def exception_name(exc):
     return exc.__class__.__name__
+
+
+if py38:
+    from importlib import metadata as importlib_metadata
+else:
+    import importlib_metadata  # noqa
+
+
+def importlib_metadata_get(group):
+    ep = importlib_metadata.entry_points()
+    if hasattr(ep, "select"):
+        return ep.select(group=group)
+    else:
+        return ep.get(group, ())

mako/util.py

@@ -11,6 +11,8 @@
 import re
 import timeit
 
+from .compat import importlib_metadata_get
+
 
 def update_wrapper(decorated, fn):
     decorated.__wrapped__ = fn
@@ -26,17 +28,17 @@ def __init__(self, group):
     def load(self, name):
         if name in self.impls:
             return self.impls[name]()
-        import pkg_resources
 
-        for impl in pkg_resources.iter_entry_points(self.group, name):
-            self.impls[name] = impl.load
-            return impl.load()
-        else:
-            from mako import exceptions
+        for impl in importlib_metadata_get(self.group):
+            if impl.name == name:
+                self.impls[name] = impl.load
+                return impl.load()
 
-            raise exceptions.RuntimeException(
-                "Can't load plugin %s %s" % (self.group, name)
-            )
+        from mako import exceptions
+
+        raise exceptions.RuntimeException(
+            "Can't load plugin %s %s" % (self.group, name)
+        )
 
     def register(self, name, modulepath, objname):
         def load():

setup.cfg

@@ -35,6 +35,7 @@ zip_safe = false
 
 install_requires =
     MarkupSafe >= 0.9.2
+    importlib-metadata;python_version<"3.8"
 
 [options.packages.find]
 exclude =