refactor: remove usage of imp #461

Since there are no reasonable alternatives to imp in python2.7,
try importing python3 modules and if that fails, fall back to the
previous method. However this will remove that annoying
DeprecationWarning for everyone using python3.

fix #478

pynvim/plugin/host.py

@@ -1,5 +1,4 @@
 """Implements a Nvim host for python plugins."""
-import imp
 import inspect
 import logging
 import os
@@ -9,7 +8,7 @@
 from traceback import format_exc
 
 from pynvim.api import decode_if_bytes, walk
-from pynvim.compat import IS_PYTHON3, find_module
+from pynvim.compat import IS_PYTHON3
 from pynvim.msgpack_rpc import ErrorResponse
 from pynvim.plugin import script_host
 from pynvim.util import format_exc_skip, get_client_info
@@ -23,6 +22,27 @@
 host_method_spec = {"poll": {}, "specs": {"nargs": 1}, "shutdown": {}}
 
 
+def handle_import(directory, name):
+    """Import a python file given a known location.
+
+    Currently works on both python2 or 3.
+    """
+    try:  # Python3
+        from importlib.util import module_from_spec, spec_from_file_location
+    except ImportError:  # Python2.7
+        import imp
+        from pynvim.compat import find_module
+        file, pathname, descr = find_module(name, [directory])
+        module = imp.load_module(name, file, pathname, descr)
+        return module
+    else:
+        spec = spec_from_file_location(name, location=directory)
+        if spec is not None:
+            return module_from_spec(spec)
+        else:
+            raise ImportError
+
+
 class Host(object):
 
     """Nvim host for python plugins.
@@ -161,8 +181,10 @@ def _load(self, plugins):
                     has_script = True
                 else:
                     directory, name = os.path.split(os.path.splitext(path)[0])
-                    file, pathname, descr = find_module(name, [directory])
-                    module = imp.load_module(name, file, pathname, descr)
+                    try:
+                        module = handle_import(directory, name)
+                    except ImportError:
+                        return
                 handlers = []
                 self._discover_classes(module, handlers, path)
                 self._discover_functions(module, handlers, path, False)
@@ -232,12 +254,12 @@ def predicate(o):
             if sync:
                 if method in self._request_handlers:
                     raise Exception(('Request handler for "{}" is '
-                                    + 'already registered').format(method))
+                                     + 'already registered').format(method))
                 self._request_handlers[method] = fn_wrapped
             else:
                 if method in self._notification_handlers:
                     raise Exception(('Notification handler for "{}" is '
-                                    + 'already registered').format(method))
+                                     + 'already registered').format(method))
                 self._notification_handlers[method] = fn_wrapped
             if hasattr(fn, '_nvim_rpc_spec'):
                 specs.append(fn._nvim_rpc_spec)