envpersist.py extension - boosts %env to remember env variables

IPython/Extensions/envpersist.py

@@ -0,0 +1,78 b''
+# -*- coding: utf-8 -*-
+"""
+%store magic for lightweight persistence.
+
+Stores variables, aliases etc. in PickleShare database.
+
+$Id: iplib.py 1107 2006-01-30 19:02:20Z vivainio $
+"""
+
+import IPython.ipapi
+ip = IPython.ipapi.get()
+
+import os,sys
+
+def restore_env(self):
+    ip = self.getapi()
+    env = ip.db.get('stored_env', {'set' : {}, 'add' : []})
+    for k,v in env['set'].items():
+        #print "restore alias",k,v # dbg
+        os.environ[k] = v
+        self.alias_table[k] = v
+    for k,v in env['add']:
+        os.environ[k] = os.environ.get(k,"") + v
+
+  
+ip.set_hook('late_startup_hook', restore_env)
+
+def persist_env(self, parameter_s=''):
+    """ Store environment variables persistently
+    
+    IPython remembers the values across sessions, which is handy to avoid 
+    editing startup files.
+    
+    %env - Show all environment variables
+    %env VISUAL=jed  - set VISUAL to jed
+    %env PATH+=;/foo - append ;foo to PATH
+    %env PATH+=;/foo - also append ;bar to PATH
+    %env VISUAL=del  - forget VISUAL persistent val
+    
+    """
+    
+    
+    
+    if not parameter_s.strip():
+        return os.environ.data
+    
+    parts = parameter_s.strip().split('=')    
+    
+    ip = self.getapi()
+    db = ip.db
+    env = ip.db.get('stored_env', {'set' : {}, 'add' : []})
+
+    if len(parts) == 2:
+        k,v = parts
+        
+    
+    if v == 'del':
+        if k in env['set']:
+            del env['set'][k]
+        env['add'] = [el for el in env['add'] if el[0] == k]
+        #del os.environ[k]
+        print "Forgot",k,"(for next session)"
+        
+    elif k.endswith('+'):
+        k = k[:-1]
+        env['add'].append((k,v))
+        os.environ[k] += v
+    else:
+        env['set'][k] = v
+        print "Setting",k,"to",v
+        os.environ[k] = os.environ.get(k,"") + v
+        
+    db['stored_env'] = env
+    
+
+    
+
+ip.expose_magic('env', persist_env)

doc/ChangeLog

@@ -1,3 +1,9 b''
[phone]  Ville Vainio  <[e-mail]>
+
+	* Extensions/envpersist.py: Turbocharged %env that remembers
+	env vars across sessions; e.g. "%env PATH+=;/opt/scripts" or
+	"%env VISUAL=jed".
+
 2007-01-05  Fernando Perez  <[e-mail]>
 
 	* IPython/iplib.py (showtraceback): ensure that we correctly call