ipapi.get() only returns dummy obj when asked for

IPython/ipapi.py

@@ -1,321 +1,325 b''
 ''' IPython customization API
 
 Your one-stop module for configuring & extending ipython
 
 The API will probably break when ipython 1.0 is released, but so 
 will the other configuration method (rc files).
 
 All names prefixed by underscores are for internal use, not part 
 of the public api.
 
 Below is an example that you can just put to a module and import from ipython. 
 
 A good practice is to install the config script below as e.g. 
 
 ~/.ipython/my_private_conf.py
 
 And do 
 
 import_mod my_private_conf 
 
 in ~/.ipython/ipythonrc
 
 That way the module is imported at startup and you can have all your
 personal configuration (as opposed to boilerplate ipythonrc-PROFILENAME 
 stuff) in there. 
 
 -----------------------------------------------
 import IPython.ipapi
 ip = IPython.ipapi.get()
 
 def ankka_f(self, arg):
     print "Ankka",self,"says uppercase:",arg.upper()
 
 ip.expose_magic("ankka",ankka_f)
 
 ip.magic('alias sayhi echo "Testing, hi ok"')
 ip.magic('alias helloworld echo "Hello world"')
 ip.system('pwd')
 
 ip.ex('import re')
 ip.ex("""
 def funcci(a,b):
     print a+b
 print funcci(3,4)
 """)
 ip.ex("funcci(348,9)")
 
 def jed_editor(self,filename, linenum=None):
     print "Calling my own editor, jed ... via hook!"
     import os
     if linenum is None: linenum = 0
     os.system('jed +%d %s' % (linenum, filename))
     print "exiting jed"
 
 ip.set_hook('editor',jed_editor)
 
 o = ip.options
 o.autocall = 2  # FULL autocall mode
 
 print "done!"
 '''
 
 # stdlib imports
 import sys
 
 # our own
 from IPython.genutils import warn,error
  
 class TryNext(Exception):
     """Try next hook exception.
      
     Raise this in your hook function to indicate that the next hook handler
     should be used to handle the operation.  If you pass arguments to the
     constructor those arguments will be used by the next hook instead of the
     original ones.
     """
 
     def __init__(self, *args, **kwargs):
         self.args = args
         self.kwargs = kwargs
 
 # contains the most recently instantiated IPApi
 
 class IPythonNotRunning:
     """Dummy do-nothing class.
 
     Instances of this class return a dummy attribute on all accesses, which
     can be called and warns.  This makes it easier to write scripts which use
     the ipapi.get() object for informational purposes to operate both with and
     without ipython.  Obviously code which uses the ipython object for
     computations will not work, but this allows a wider range of code to
     transparently work whether ipython is being used or not."""
     
     def __str__(self):
         return "<IPythonNotRunning>"
 
     __repr__ = __str__
 
     def __getattr__(self,name):
         return self.dummy
 
     def dummy(self,*args,**kw):
         """Dummy function, which doesn't do anything but warn."""
         warn("IPython is not running, this is a dummy no-op function")
 
-_recent = IPythonNotRunning()
+_recent = None
+
 
-def get():
+def get(allow_dummy=False):
     """Get an IPApi object.
 
-    Returns an instance of IPythonNotRunning if not running under IPython.
+    If allow_dummy is true, returns an instance of IPythonNotRunning 
+    instead of None if not running under IPython.
 
     Running this should be the first thing you do when writing extensions that
     can be imported as normal modules. You can then direct all the
     configuration operations against the returned object.
     """
-
+    global _recent
+    if allow_dummy and not _recent:
+        _recent = IPythonNotRunning()
     return _recent
 
 class IPApi:
     """ The actual API class for configuring IPython 
     
     You should do all of the IPython configuration by getting an IPApi object
     with IPython.ipapi.get() and using the attributes and methods of the
     returned object."""
     
     def __init__(self,ip):
         
         # All attributes exposed here are considered to be the public API of
         # IPython.  As needs dictate, some of these may be wrapped as
         # properties.
 
         self.magic = ip.ipmagic
         
         self.system = ip.ipsystem
         
         self.set_hook = ip.set_hook
         
         self.set_custom_exc = ip.set_custom_exc
 
         self.user_ns = ip.user_ns
 
         # Session-specific data store, which can be used to store
         # data that should persist through the ipython session.
         self.meta =  ip.meta
     
         # The ipython instance provided
         self.IP = ip
 
         global _recent
         _recent = self
 
     # Use a property for some things which are added to the instance very
     # late.  I don't have time right now to disentangle the initialization
     # order issues, so a property lets us delay item extraction while
     # providing a normal attribute API.
     def get_db(self):
         """A handle to persistent dict-like database (a PickleShareDB object)"""
         return self.IP.db
 
     db = property(get_db,None,None,get_db.__doc__)
 
     def get_options(self):
         """All configurable variables."""
         return self.IP.rc
 
     options = property(get_options,None,None,get_options.__doc__)
     
     def expose_magic(self,magicname, func):
         ''' Expose own function as magic function for ipython 
     
         def foo_impl(self,parameter_s=''):
             """My very own magic!. (Use docstrings, IPython reads them)."""
             print 'Magic function. Passed parameter is between < >: <'+parameter_s+'>'
             print 'The self object is:',self
     
         ipapi.expose_magic("foo",foo_impl)
         '''
                 
         import new
         im = new.instancemethod(func,self.IP, self.IP.__class__)
         setattr(self.IP, "magic_" + magicname, im)
     
     def ex(self,cmd):
         """ Execute a normal python statement in user namespace """
         exec cmd in self.user_ns
     
     def ev(self,expr):
         """ Evaluate python expression expr in user namespace 
         
         Returns the result of evaluation"""
         return eval(expr,self.user_ns)
     
     def runlines(self,lines):
         """ Run the specified lines in interpreter, honoring ipython directives.
         
         This allows %magic and !shell escape notations.
         
         Takes either all lines in one string or list of lines.
         """
         if isinstance(lines,basestring):
             self.IP.runlines(lines)
         else:
             self.IP.runlines('\n'.join(lines))
 
     def to_user_ns(self,*vars):
         """Inject a group of variables into the IPython user namespace.
 
         Inputs:
 
          - *vars: one or more variables from the caller's namespace to be put
          into the interactive IPython namespace.  The arguments can be given
          in one of two forms, but ALL arguments must follow the same
          convention (the first is checked and the rest are assumed to follow
          it):
          
            a) All strings, naming variables in the caller.  These names are
            evaluated in the caller's frame and put in, with the same name, in
            the IPython namespace.
 
            b) Pairs of (name, value), where the name is a string (a valid
            python identifier).  In this case, the value is put into the
            IPython namespace labeled by the given name.  This allows you to
            rename your local variables so they don't collide with other names
            you may already be using globally, or elsewhere and which you also
            want to propagate.
 
 
         This utility routine is meant to ease interactive debugging work,
         where you want to easily propagate some internal variable in your code
         up to the interactive namespace for further exploration.
 
         When you run code via %run, globals in your script become visible at
         the interactive prompt, but this doesn't happen for locals inside your
         own functions and methods.  Yet when debugging, it is common to want
         to explore some internal variables further at the interactive propmt.
 
         Examples:
 
         To use this, you first must obtain a handle on the ipython object as
         indicated above, via:
 
         import IPython.ipapi
         ip = IPython.ipapi.get()
 
         Once this is done, inside a routine foo() where you want to expose
         variables x and y, you do the following:
 
         def foo():
             ...
             x = your_computation()
             y = something_else()
             
             # This pushes x and y to the interactive prompt immediately, even
             # if this routine crashes on the next line after:
             ip.to_user_ns('x','y')
             ...
             # return
 
         The following example shows you how to rename variables to avoid
         clashes:
 
         def bar():
             ...
             x,y,z,w = foo()
             
             # Push these variables with different names, so they don't
             # overwrite x and y from before
             ip.to_user_ns(('x1',x),('y1',y),('z1',z),('w1',w))
             # which is more conveniently written as:
             ip.to_user_ns(*zip(('x1','y1','z1','w1'),(x,y,z,w)))
             
             ...
             # return """
 
         # print 'vars given:',vars # dbg
         # Get the caller's frame to evaluate the given names in
         cf = sys._getframe(1)
         
         # XXX fix this after Ville replies...
         user_ns = self.user_ns
 
         if isinstance(vars[0],basestring):
             # assume that all variables are given as strings
             try:
                 for name in vars:
                     user_ns[name] = eval(name,cf.f_globals,cf.f_locals)
             except:
                 error('could not get var. %s from %s' %
                       (name,cf.f_code.co_name))
 
         else:
             # assume they are all given as pairs of name,object
             user_ns.update(dict(vars))
 
 
 def launch_new_instance(user_ns = None):
     """ Create and start a new ipython instance.
     
     This can be called even without having an already initialized 
     ipython session running.
     
     This is also used as the egg entry point for the 'ipython' script.
     
     """
     ses = create_session(user_ns)
     ses.mainloop()
 
 
 def create_session(user_ns = None):    
     """ Creates, but does not launch an IPython session.
     
     Later on you can call obj.mainloop() on the returned object.
     
     This should *not* be run when a session exists already.
     
     """
     if user_ns is not None: 
         user_ns["__name__"] = user_ns.get("__name__",'ipy_session')
     import IPython
     return IPython.Shell.start(user_ns = user_ns)