XDG updates

docs/tutorial.rst

@@ -240,6 +240,12 @@ XONSH_SHOW_TRACEBACK       Not defined                   Controls if a traceback
 CASE_SENSITIVE_COMPLETIONS True on Linux otherwise False Sets whether completions should
                                                          be case sesistive or case
                                                          insensitive.
+XONSH_DATA_DIR             $XDG_DATA_HOME/xonsh          This is the location where
+                                                         xonsh data files are stored, 
+                                                         such as history.
+XONSH_CONFIG_DIR           $XDG_CONFIG_HOME/xonsh        This is location where xonsh
+                                                         configuration information is
+                                                         stored.
 ========================== ============================= ================================
 
 Environment Lookup with ``${}``

xonsh/environ.py

@@ -523,6 +523,19 @@ def xonshrc_context(rcfile=None, execer=None):
     return env
 
 
+def recursive_base_env_update(env):
+    """Updates the environment with members that may rely on previously defined
+    members. Takes an env as its argument.
+    """
+    home = os.path.expanduser('~')
+    if 'XONSH_DATA_DIR' not in env:
+        xdgdh = env.get('XDG_DATA_HOME', os.path.join(home, '.local', 'share'))
+        env['XONSH_DATA_DIR'] = os.path.join(xdgdh, 'xonsh')
+    if 'XONSH_CONFIG_DIR' not in env:
+        xdgch = env.get('XDG_CONFIG_HOME', os.path.join(home, '.config'))
+        env['XONSH_CONFIG_DIR'] = os.path.join(xdgch, 'xonsh')
+
+
 def default_env(env=None):
     """Constructs a default xonsh environment."""
     # in order of increasing precedence
@@ -548,7 +561,8 @@ def default_env(env=None):
                 del ctx[ev]
 
         ctx['PWD'] = _get_cwd()
-
+    # finalize env
+    recursive_base_env_update(ctx)
     if env is not None:
         ctx.update(env)
     return ctx

xonsh/history.py

@@ -12,13 +12,20 @@ from xonsh import lazyjson
 
 class History(object):
 
-    ordered_history = []
+    def __init__(self, filename=None, sessionid=None, buffersize=100):
+        """Represents a xonsh session's history as an in-memory buffer that is
+        periodically flushed to disk.
 
-    def __init__(self, hid=None):
-        #env = builtins.__xonsh_env__
-        #self.hf = env.get('XONSH_HISTORY_FILE',
-        #        os.path.expanduser('~/.xonsh_history.json'))
-        self.hf = '~/.xonsh-history-{0}.json'.format(uuid.uuid4())
+        Parameters
+        ----------
+        filename : str, optional
+            
+        """
+        self.sessionid = uuid.uuid4() if sessionid is None else sessionid
+        self.filename = '~/xonsh-{0}.json'.format(self.sessionid) \
+            if filename is None else filename
+        self.buffer = []
+        self.buffersize = buffersize
 
     def open_history(self):
         """Loads previous history from ~/.xonsh_history.json or