Add support for proper deletion, raising KeyError where appropriate

Fixes #402

Author: blueyed

pynvim/api/common.py

@@ -6,6 +6,10 @@
 from ..compat import unicode_errors_default
 
 
+class NvimError(Exception):
+    pass
+
+
 class Remote(object):
 
     """Base class for Nvim objects(buffer/window/tabpage).
@@ -26,7 +30,8 @@ def __init__(self, session, code_data):
         self.handle = unpackb(code_data[1])
         self.api = RemoteApi(self, self._api_prefix)
         self.vars = RemoteMap(self, self._api_prefix + 'get_var',
-                              self._api_prefix + 'set_var')
+                              self._api_prefix + 'set_var',
+                              self._api_prefix + 'del_var')
         self.options = RemoteMap(self, self._api_prefix + 'get_option',
                                  self._api_prefix + 'set_option')
 
@@ -65,8 +70,16 @@ def __getattr__(self, name):
         return functools.partial(self._obj.request, self._api_prefix + name)
 
 
-class RemoteMap(object):
+def transform_keyerror(exc):
+    if isinstance(exc, NvimError):
+        if exc.args[0].startswith('Key not found:'):
+            return KeyError(exc.args[0])
+        if exc.args[0].startswith('Invalid option name:'):
+            return KeyError(exc.args[0])
+    return exc
 
+
+class RemoteMap(object):
     """Represents a string->object map stored in Nvim.
 
     This is the dict counterpart to the `RemoteSequence` class, but it is used
@@ -75,17 +88,23 @@ class RemoteMap(object):
 
     It is used to provide a dict-like API to vim variables and options.
     """
+    _set = None
+    _del = None
 
-    def __init__(self, obj, get_method, set_method=None):
+    def __init__(self, obj, get_method, set_method=None, del_method=None):
         """Initialize a RemoteMap with session, getter/setter."""
         self._get = functools.partial(obj.request, get_method)
-        self._set = None
         if set_method:
             self._set = functools.partial(obj.request, set_method)
+        if del_method:
+            self._del = functools.partial(obj.request, del_method)
 
     def __getitem__(self, key):
         """Return a map value by key."""
-        return self._get(key)
+        try:
+            return self._get(key)
+        except NvimError as exc:
+            raise transform_keyerror(exc)
 
     def __setitem__(self, key, value):
         """Set a map value by key(if the setter was provided)."""
@@ -95,9 +114,12 @@ def __setitem__(self, key, value):
 
     def __delitem__(self, key):
         """Delete a map value by associating None with the key."""
-        if not self._set:
+        if not self._del:
             raise TypeError('This dict is read-only')
-        return self._set(key, None)
+        try:
+            return self._del(key)
+        except NvimError as exc:
+            raise transform_keyerror(exc)
 
     def __contains__(self, key):
         """Check if key is present in the map."""
@@ -110,8 +132,8 @@ def __contains__(self, key):
     def get(self, key, default=None):
         """Return value for key if present, else a default value."""
         try:
-            return self._get(key)
-        except Exception:
+            return self.__getitem__(key)
+        except KeyError:
             return default
 
 

pynvim/api/nvim.py

@@ -8,7 +8,7 @@
 from msgpack import ExtType
 
 from .buffer import Buffer
-from .common import (Remote, RemoteApi, RemoteMap, RemoteSequence,
+from .common import (NvimError, Remote, RemoteApi, RemoteMap, RemoteSequence,
                      decode_if_bytes, walk)
 from .tabpage import Tabpage
 from .window import Window
@@ -107,8 +107,8 @@ def __init__(self, session, channel_id, metadata, types,
         self.version = Version(**version)
         self.types = types
         self.api = RemoteApi(self, 'nvim_')
-        self.vars = RemoteMap(self, 'nvim_get_var', 'nvim_set_var')
-        self.vvars = RemoteMap(self, 'nvim_get_vvar', None)
+        self.vars = RemoteMap(self, 'nvim_get_var', 'nvim_set_var', 'nvim_del_var')
+        self.vvars = RemoteMap(self, 'nvim_get_vvar', None, None)
         self.options = RemoteMap(self, 'nvim_get_option', 'nvim_set_option')
         self.buffers = Buffers(self)
         self.windows = RemoteSequence(self, 'nvim_list_wins')
@@ -575,7 +575,3 @@ def __call__(self, *args, **kwargs):
         pattern = "return {}(...)" if not async_ else "{}(...)"
         code = pattern.format(self.name)
         return self._nvim.exec_lua(code, *args, **kwargs)
-
-
-class NvimError(Exception):
-    pass

test/test_buffer.py

@@ -1,5 +1,7 @@
 import os
 
+import pytest
+from pynvim.api import NvimError
 from pynvim.compat import IS_PYTHON3
 
 
@@ -74,6 +76,17 @@ def test_vars(vim):
     vim.current.buffer.vars['python'] = [1, 2, {'3': 1}]
     assert vim.current.buffer.vars['python'] == [1, 2, {'3': 1}]
     assert vim.eval('b:python') == [1, 2, {'3': 1}]
+    assert vim.current.buffer.vars.get('python') == [1, 2, {'3': 1}]
+
+    del vim.current.buffer.vars['python']
+    with pytest.raises(KeyError):
+        vim.current.buffer.vars['python']
+    assert vim.eval('exists("b:python")') == 0
+
+    with pytest.raises(KeyError):
+        del vim.current.buffer.vars['python']
+
+    assert vim.current.buffer.vars.get('python', 'default') == 'default'
 
 
 def test_api(vim):
@@ -95,6 +108,10 @@ def test_options(vim):
     # Doesn't change the global value
     assert vim.options['define'] == r'^\s*#\s*define'
 
+    with pytest.raises(KeyError) as excinfo:
+        vim.current.buffer.options['doesnotexist']
+    assert excinfo.value.args == ("Invalid option name: 'doesnotexist'",)
+
 
 def test_number(vim):
     curnum = vim.current.buffer.number
@@ -154,10 +171,10 @@ def test_invalid_utf8(vim):
 
 
 def test_get_exceptions(vim):
-    with pytest.raises(vim.error) as excinfo:
+    with pytest.raises(KeyError) as excinfo:
         vim.current.buffer.options['invalid-option']
 
-    assert isinstance(excinfo.value, KeyError)
+    assert not isinstance(excinfo.value, NvimError)
     assert excinfo.value.args == ("Invalid option name: 'invalid-option'",)
 
 

test/test_tabpage.py

@@ -1,3 +1,6 @@
+import pytest
+
+
 def test_windows(vim):
     vim.command('tabnew')
     vim.command('vsplit')
@@ -12,6 +15,17 @@ def test_vars(vim):
     vim.current.tabpage.vars['python'] = [1, 2, {'3': 1}]
     assert vim.current.tabpage.vars['python'] == [1, 2, {'3': 1}]
     assert vim.eval('t:python') == [1, 2, {'3': 1}]
+    assert vim.current.tabpage.vars.get('python') == [1, 2, {'3': 1}]
+
+    del vim.current.tabpage.vars['python']
+    with pytest.raises(KeyError):
+        vim.current.tabpage.vars['python']
+    assert vim.eval('exists("t:python")') == 0
+
+    with pytest.raises(KeyError):
+        del vim.current.tabpage.vars['python']
+
+    assert vim.current.tabpage.vars.get('python', 'default') == 'default'
 
 
 def test_valid(vim):

test/test_vim.py

@@ -99,6 +99,17 @@ def test_vars(vim):
     vim.vars['python'] = [1, 2, {'3': 1}]
     assert vim.vars['python'], [1, 2 == {'3': 1}]
     assert vim.eval('g:python'), [1, 2 == {'3': 1}]
+    assert vim.vars.get('python') == [1, 2, {'3': 1}]
+
+    del vim.vars['python']
+    with pytest.raises(KeyError):
+        vim.vars['python']
+    assert vim.eval('exists("g:python")') == 0
+
+    with pytest.raises(KeyError):
+        del vim.vars['python']
+
+    assert vim.vars.get('python', 'default') == 'default'
 
 
 def test_options(vim):

test/test_window.py

@@ -1,3 +1,6 @@
+import pytest
+
+
 def test_buffer(vim):
     assert vim.current.buffer == vim.windows[0].buffer
     vim.command('new')
@@ -40,6 +43,17 @@ def test_vars(vim):
     vim.current.window.vars['python'] = [1, 2, {'3': 1}]
     assert vim.current.window.vars['python'] == [1, 2, {'3': 1}]
     assert vim.eval('w:python') == [1, 2, {'3': 1}]
+    assert vim.current.window.vars.get('python') == [1, 2, {'3': 1}]
+
+    del vim.current.window.vars['python']
+    with pytest.raises(KeyError):
+        vim.current.window.vars['python']
+    assert vim.eval('exists("w:python")') == 0
+
+    with pytest.raises(KeyError):
+        del vim.current.window.vars['python']
+
+    assert vim.current.window.vars.get('python', 'default') == 'default'
 
 
 def test_options(vim):
@@ -50,6 +64,10 @@ def test_options(vim):
     assert vim.current.window.options['statusline'] == 'window-status'
     assert vim.options['statusline'] == ''
 
+    with pytest.raises(KeyError) as excinfo:
+        vim.current.window.options['doesnotexist']
+    assert excinfo.value.args == ("Invalid option name: 'doesnotexist'",)
+
 
 def test_position(vim):
     height = vim.windows[0].height