Drop old python versions, add type annotations #492

Fixes #422 

Dropping support for python 3.6 and earlier
https://www.python.org/downloads/release/python-3510/

This adds coverage for most of the public API, but some areas aren't covered:
* `script_host.py` is ignored entirely
* `host.py` is ignored entirely
* the `msgpack_rpc` submodule has partial coverage
* there are some Any annotations sprinkled around on some of the more
  complex functions

.gitignore

@@ -10,6 +10,7 @@ venv
 .eggs
 .tox
 .pytest_cache
+.coverage*
 
 # Sphinx documentation
 docs/_build/

README.md

@@ -28,8 +28,8 @@ Python Plugin API
 -----------------
 
 Pynvim supports python _remote plugins_ (via the language-agnostic Nvim rplugin
-interface), as well as _Vim plugins_ (via the `:python[3]` interface). Thus when
-pynvim is installed Neovim will report support for the `+python[3]` Vim feature.
+interface), as well as _Vim plugins_ (via the `:python3` interface). Thus when
+pynvim is installed Neovim will report support for the `+python3` Vim feature.
 
 The rplugin interface allows plugins to handle vimL function calls as well as
 defining commands and autocommands, and such plugins can operate asynchronously

docs/development.rst

@@ -3,7 +3,6 @@ Development
 
 If you change the code, you need to run::
 
-    pip2 install .
     pip3 install .
 
 for the changes to have effect.
@@ -45,9 +44,9 @@ You can run the plugin host in Neovim with logging enabled to debug errors::
     NVIM_PYTHON_LOG_FILE=logfile NVIM_PYTHON_LOG_LEVEL=DEBUG nvim
 
 As more than one Python host process might be started,
-the log filenames take the pattern ``logfile_pyX_KIND``
-where ``X`` is the major python version (2 or 3)
-and ``KIND`` is either "rplugin" or "script" (for the ``:python[3]`` script interface).
+the log filenames take the pattern ``logfile_py3_KIND``
+where ``KIND`` is either "rplugin" or "script" (for the ``:python3`` script
+interface).
 
 If the host cannot start at all,
 the error could be found in ``~/.nvimlog`` if ``nvim`` was compiled with logging.

docs/installation.rst

@@ -1,25 +1,18 @@
 Installation
 ============
 
-The Neovim Python client supports Python 2.7, and 3.4 or later.
+The Neovim Python client supports Python 3.7 or later.
 
 Using pip
 ---------
 
 You can install the package without being root by adding the ``--user`` flag::
 
-    pip2 install --user pynvim
     pip3 install --user pynvim
 
-.. note::
-
-    If you only use one of python2 or python3,
-    it is enough to install that version.
-
 If you follow Neovim HEAD, make sure to upgrade ``pynvim`` when you upgrade
 Neovim::
 
-    pip2 install --upgrade pynvim
     pip3 install --upgrade pynvim
 
 Install from source
@@ -32,5 +25,4 @@ Clone the repository somewhere on your disk and enter to the repository::
 
 Now you can install it on your system::
 
-    pip2 install .
     pip3 install .

pynvim/__init__.py

@@ -5,14 +5,20 @@
 import logging
 import os
 import sys
+from types import SimpleNamespace as Version
+from typing import List, cast, overload
 
 from pynvim.api import Nvim, NvimError
-from pynvim.compat import IS_PYTHON3
-from pynvim.msgpack_rpc import (ErrorResponse, child_session, socket_session,
-                                stdio_session, tcp_session)
+from pynvim.msgpack_rpc import (ErrorResponse, Session, TTransportType, child_session,
+                                socket_session, stdio_session, tcp_session)
 from pynvim.plugin import (Host, autocmd, command, decode, encoding, function,
                            plugin, rpc_export, shutdown_hook)
-from pynvim.util import VERSION, Version
+from pynvim.util import VERSION
+
+if sys.version_info < (3, 8):
+    from typing_extensions import Literal
+else:
+    from typing import Literal
 
 
 __all__ = ('tcp_session', 'socket_session', 'stdio_session', 'child_session',
@@ -22,7 +28,7 @@
            'ErrorResponse')
 
 
-def start_host(session=None):
+def start_host(session: Session = None) -> None:
     """Promote the current process into python plugin host for Nvim.
 
     Start msgpack-rpc event loop for `session`, listening for Nvim requests
@@ -77,8 +83,30 @@ def start_host(session=None):
     host.start(plugins)
 
 
-def attach(session_type, address=None, port=None,
-           path=None, argv=None, decode=None):
+@overload
+def attach(session_type: Literal['tcp'], address: str, port: int = 7450) -> Nvim: ...
+
+
+@overload
+def attach(session_type: Literal['socket'], *, path: str) -> Nvim: ...
+
+
+@overload
+def attach(session_type: Literal['child'], *, argv: List[str]) -> Nvim: ...
+
+
+@overload
+def attach(session_type: Literal['stdio']) -> Nvim: ...
+
+
+def attach(
+    session_type: TTransportType,
+    address: str = None,
+    port: int = 7450,
+    path: str = None,
+    argv: List[str] = None,
+    decode: Literal[True] = True
+) -> Nvim:
     """Provide a nicer interface to create python api sessions.
 
     Previous machinery to create python api sessions is still there. This only
@@ -107,22 +135,21 @@ def attach(session_type, address=None, port=None,
 
 
     """
-    session = (tcp_session(address, port) if session_type == 'tcp' else
-               socket_session(path) if session_type == 'socket' else
-               stdio_session() if session_type == 'stdio' else
-               child_session(argv) if session_type == 'child' else
-               None)
+    session = (
+        tcp_session(cast(str, address), port) if session_type == 'tcp' else
+        socket_session(cast(str, path)) if session_type == 'socket' else
+        stdio_session() if session_type == 'stdio' else
+        child_session(cast(List[str], argv)) if session_type == 'child' else
+        None
+    )
 
     if not session:
         raise Exception('Unknown session type "%s"' % session_type)
 
-    if decode is None:
-        decode = IS_PYTHON3
-
     return Nvim.from_session(session).with_decode(decode)
 
 
-def setup_logging(name):
+def setup_logging(name: str) -> None:
     """Setup logging according to environment variables."""
     logger = logging.getLogger(__name__)
     if 'NVIM_PYTHON_LOG_FILE' in os.environ:
@@ -144,13 +171,3 @@ def setup_logging(name):
                 logger.warning('Invalid NVIM_PYTHON_LOG_LEVEL: %r, using INFO.',
                                env_log_level)
         logger.setLevel(level)
-
-
-# Required for python 2.6
-class NullHandler(logging.Handler):
-    def emit(self, record):
-        pass
-
-
-if not logging.root.handlers:
-    logging.root.addHandler(NullHandler())