Refactor legacy vim module to subclass

Author: bfredl

neovim/api/nvim.py

@@ -32,9 +32,10 @@ class Nvim(object):
     from a raw `Session` instance.
 
     Subsequent instances for the same session can be created by calling the
-    `with_hook` instance method and passing a SessionHook instance. This can
-    be useful to have multiple `Nvim` objects that behave differently without
-    one affecting the other.
+    `with_decodehook` instance method to change the decoding behavior or
+    `SubClass.from_nvim(nvim)` where `SubClass` is a subclass of `Nvim`, which
+    is useful for having multiple `Nvim` objects that behave differently
+    without one affecting the other.
     """
 
     @classmethod
@@ -60,6 +61,12 @@ def from_session(cls, session):
 
         return cls(session, channel_id, metadata, types)
 
+    @classmethod
+    def from_nvim(cls, nvim):
+        """Create a new Nvim instance from an existing instance."""
+        return cls(nvim._session, nvim.channel_id, nvim.metadata,
+                   nvim.types, nvim._decodehook)
+
     def __init__(self, session, channel_id, metadata, types, decodehook=None):
         """Initialize a new Nvim instance. This method is module-private."""
         self._session = session

neovim/plugin/script_host.py

@@ -6,7 +6,7 @@
 import sys
 
 from .decorators import plugin, rpc_export
-from ..api import SessionHook
+from ..api import Nvim
 
 __all__ = ('ScriptHost',)
 
@@ -36,7 +36,7 @@ def __init__(self, nvim):
         nvim.script_context = self.module
         # it seems some plugins assume 'sys' is already imported, so do it now
         exec('import sys', self.module.__dict__)
-        self.legacy_vim = nvim.with_hook(LegacyEvalHook())
+        self.legacy_vim = LegacyVim.from_nvim(nvim)
         sys.modules['vim'] = self.legacy_vim
 
     def setup(self, nvim):
@@ -161,20 +161,14 @@ def writelines(self, seq):
         self.redirect_handler('\n'.join(seq))
 
 
-class LegacyEvalHook(SessionHook):
-
-    """Injects legacy `vim.eval` behavior to a Nvim instance."""
-
-    def __init__(self):
-        super(LegacyEvalHook, self).__init__(from_nvim=self._string_eval)
-
-    def _string_eval(self, obj, session, method, kind):
-        if method == 'vim_eval':
-            if IS_PYTHON3:
-                if isinstance(obj, (int, float)):
-                    return str(obj)
-            elif isinstance(obj, (int, long, float)):
+class LegacyVim(Nvim):
+    def eval(self, expr):
+        obj = self.request("vim_eval", expr)
+        if IS_PYTHON3:
+            if isinstance(obj, (int, float)):
                 return str(obj)
+        elif isinstance(obj, (int, long, float)):
+            return str(obj)
         return obj