Remove support for persistent memoization

A different form of persistent memoization should be reimplemented later.

Refs #159.

powerline/lib/memoize.py

@@ -1,11 +1,5 @@
 # -*- coding: utf-8 -*-
 
-try:
-	import cPickle as pickle
-except ImportError:
-	import pickle
-import os
-import tempfile
 import time
 
 
@@ -13,11 +7,9 @@ class memoize(object):
 	'''Memoization decorator with timeout.'''
 	_cache = {}
 
-	def __init__(self, timeout, additional_key=None, persistent=False, persistent_file=None):
+	def __init__(self, timeout, additional_key=None):
 		self.timeout = timeout
 		self.additional_key = additional_key
-		self.persistent = persistent
-		self.persistent_file = persistent_file or os.path.join(tempfile.gettempdir(), 'powerline-cache')
 
 	def __call__(self, func):
 		def decorated_function(*args, **kwargs):
@@ -25,27 +17,11 @@ class memoize(object):
 				key = (func.__name__, args, tuple(kwargs.items()), self.additional_key())
 			else:
 				key = (func.__name__, args, tuple(kwargs.items()))
-			if self.persistent:
-				try:
-					with open(self.persistent_file, 'rb') as fileobj:
-						self._cache = pickle.load(fileobj)
-				except (IOError, EOFError, ValueError):
-					self._cache = {}
 			cached = self._cache.get(key, None)
 			if cached is None or time.time() - cached['time'] > self.timeout:
 				cached = self._cache[key] = {
 					'result': func(*args, **kwargs),
 					'time': time.time(),
 					}
-				if self.persistent:
-					try:
-						with open(self.persistent_file, 'wb') as fileobj:
-							pickle.dump(self._cache, fileobj)
-					except IOError:
-						# Unable to write to file
-						pass
-					except TypeError:
-						# Unable to pickle function result
-						pass
 			return cached['result']
 		return decorated_function

powerline/segments/common.py

@@ -101,7 +101,7 @@ def date(format='%Y-%m-%d'):
 	return datetime.now().strftime(format)
 
 
-@memoize(600, persistent=True)
+@memoize(600)
 def external_ip(query_url='http://ipv4.icanhazip.com/'):
 	return _urllib_read(query_url).strip()
 
@@ -123,7 +123,7 @@ def uptime(format='{days:02d}d {hours:02d}h {minutes:02d}m'):
 	return format.format(days=int(days), hours=hours, minutes=minutes)
 
 
-@memoize(1800, persistent=True)
+@memoize(1800)
 def weather(unit='c', location_query=None):
 	import json
 
@@ -232,7 +232,7 @@ def virtualenv():
 	return os.path.basename(os.environ.get('VIRTUAL_ENV', '')) or None
 
 
-@memoize(60, persistent=True)
+@memoize(60)
 def email_imap_alert(username, password, server='imap.gmail.com', port=993, folder='INBOX'):
 	import imaplib
 	import re