Rework memoize class

- Removed *args: segments are not receiveing any non-keyword arguments so no
  need to bother with *args at all.
- Replaced additional_cache_key with cache_key: all functions that formerly used
  additional_cache_key appear not to need initial arguments as cache keys. It
  also simplifies the code.
- Made _cache be defined in __init__, it is much easier to implement cache
  purging this way.

Ref #205
Fixes #208

powerline/lib/memoize.py

@@ -4,28 +4,28 @@ from functools import wraps
 import time
 
 
+def default_cache_key(**kwargs):
+	return frozenset(kwargs.items())
+
+
 class memoize(object):
 	'''Memoization decorator with timeout.'''
-	_cache = {}
-
-	def __init__(self, timeout, additional_key=None):
+	def __init__(self, timeout, cache_key=default_cache_key):
 		self.timeout = timeout
-		self.additional_key = additional_key
+		self.cache_key = cache_key
+		self._cache = {}
 
 	def __call__(self, func):
 		@wraps(func)
-		def decorated_function(*args, **kwargs):
-			if self.additional_key:
-				key = (func.__name__, args, self.additional_key(*args, **kwargs))
-			else:
-				key = (func.__name__, args)
+		def decorated_function(**kwargs):
+			key = self.cache_key(**kwargs)
 			try:
 				cached = self._cache.get(key, None)
 			except TypeError:
-				return func(*args, **kwargs)
+				return func(**kwargs)
 			if cached is None or time.time() - cached['time'] > self.timeout:
 				cached = self._cache[key] = {
-					'result': func(*args, **kwargs),
+					'result': func(**kwargs),
 					'time': time.time(),
 					}
 			return cached['result']

powerline/segments/common.py

@@ -34,7 +34,7 @@ def user():
 def branch():
 	'''Return the current VCS branch.'''
 	from powerline.lib.vcs import guess
-	repo = guess(os.path.abspath(os.getcwd()))
+	repo = guess(path=os.path.abspath(os.getcwd()))
 	if repo:
 		return repo.branch()
 	return None

powerline/segments/vim.py

@@ -47,7 +47,7 @@ mode_translations = {
 }
 
 
-def bufnr(segment_info, *args, **kwargs):
+def bufnr(segment_info, **kwargs):
 	'''Used for cache key, returns current buffer number'''
 	return segment_info['bufnr']
 
@@ -157,7 +157,7 @@ def file_name(segment_info, display_no_file=False, no_file_text='[No file]'):
 
 
 @requires_segment_info
-@memoize(2, additional_key=bufnr)
+@memoize(2, cache_key=bufnr)
 def file_size(segment_info, suffix='B', binary_prefix=False):
 	'''Return file size.
 
@@ -254,10 +254,10 @@ def modified_buffers(text=u'+', join_str=','):
 
 
 @requires_segment_info
-@memoize(2)
+@memoize(2, cache_key=bufnr)
 def branch(segment_info):
 	'''Return the current working branch.'''
-	repo = guess(os.path.abspath(segment_info['buffer'].name or os.getcwd()))
+	repo = guess(path=os.path.abspath(segment_info['buffer'].name or os.getcwd()))
 	if repo:
 		return repo.branch()
 	return None
@@ -265,12 +265,12 @@ def branch(segment_info):
 
 # TODO Drop cache on BufWrite event
 @requires_segment_info
-@memoize(2, additional_key=bufnr)
+@memoize(2, cache_key=bufnr)
 def file_vcs_status(segment_info):
 	'''Return the VCS status for this buffer.'''
 	name = segment_info['buffer'].name
 	if name and not getbufvar(segment_info['bufnr'], '&buftype'):
-		repo = guess(os.path.abspath(name))
+		repo = guess(path=os.path.abspath(name))
 		if repo:
 			status = repo.status(os.path.relpath(name, repo.directory))
 			if not status:
@@ -288,10 +288,10 @@ def file_vcs_status(segment_info):
 
 
 @requires_segment_info
-@memoize(2)
+@memoize(2, cache_key=bufnr)
 def repository_status(segment_info):
 	'''Return the status for the current repo.'''
-	repo = guess(os.path.abspath(segment_info['buffer'].name or os.getcwd()))
+	repo = guess(path=os.path.abspath(segment_info['buffer'].name or os.getcwd()))
 	if repo:
 		return repo.status()
 	return None