IPython/ipapi.py

''' 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 __builtin__
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 __init__(self,warn=True):
        if warn:
            self.dummy = self._dummy_warn
        else:
            self.dummy = self._dummy_silent
    
    def __str__(self):
        return "<IPythonNotRunning>"

    __repr__ = __str__

    def __getattr__(self,name):
        return self.dummy

    def _dummy_warn(self,*args,**kw):
        """Dummy function, which doesn't do anything but warn."""

        warn("IPython is not running, this is a dummy no-op function")

    def _dummy_silent(self,*args,**kw):
        """Dummy function, which doesn't do anything and emits no warnings."""
        pass

_recent = None


def get(allow_dummy=False,dummy_warn=True):
    """Get an IPApi object.

    If allow_dummy is true, returns an instance of IPythonNotRunning 
    instead of None if not running under IPython.

    If dummy_warn is false, the dummy instance will be completely silent.

    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(dummy_warn)
    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

        self.set_crash_handler = ip.set_crash_handler

        # 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."""
        
        # catch typos by disabling new attribute creation. If new attr creation
        # is in fact wanted (e.g. when exposing new options), do allow_new_attr(True) 
        # for the received rc struct.
        
        self.IP.rc.allow_new_attr(False)
        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: string with variable names separated by whitespace

        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           
        
        If you need to rename variables, just use ip.user_ns with dict
        and update:
        
        # exposes variables 'foo' as 'x' and 'bar' as 'y' in IPython 
        # user namespace
        ip.user_ns.update(dict(x=foo,y=bar))    
        """

        # print 'vars given:',vars # dbg
        # Get the caller's frame to evaluate the given names in
        cf = sys._getframe(1)
        
        user_ns = self.user_ns
        
        for name in vars.split():
            try:
                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))

    def expand_alias(self,line):
        """ Expand an alias in the command line 
        
        Returns the provided command line, possibly with the first word 
        (command) translated according to alias expansion rules.
        
        [ipython]|16> _ip.expand_aliases("np myfile.txt")
                 <16> 'q:/opt/np/notepad++.exe myfile.txt'
        """
        
        pre,fn,rest = self.IP.split_user_input(line)
        res = pre + self.IP.expand_aliases(fn,rest)

    def defalias(self, name, cmd):
        """ Define a new alias
        
        _ip.defalias('bb','bldmake bldfiles')
        
        Creates a new alias named 'bb' in ipython user namespace
        """
        
        
        nargs = cmd.count('%s')
        if nargs>0 and cmd.find('%l')>=0:
            raise Exception('The %s and %l specifiers are mutually exclusive '
                            'in alias definitions.')
                  
        else:  # all looks OK
            self.IP.alias_table[name] = (nargs,cmd)            
    
    def defmacro(self, *args):
        """ Define a new macro
    
        2 forms of calling:
        
        mac = _ip.defmacro('print "hello"\nprint "world"')
        
        (doesn't put the created macro on user namespace)
        
        _ip.defmacro('build', 'bldmake bldfiles\nabld build winscw udeb')
        
        (creates a macro named 'build' in user namespace)
        """
        
        import IPython.macro
        
        if len(args) == 1:
            return IPython.macro.Macro(args[0])
        elif len(args) == 2:
            self.user_ns[args[0]] = IPython.macro.Macro(args[1])
        else:
            return Exception("_ip.defmacro must be called with 1 or 2 arguments")
        
        

def launch_new_instance(user_ns = None):
    """ Make 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 = make_session(user_ns)
    ses.mainloop()


def make_user_ns(user_ns = None):
    """Return a valid user interactive namespace.

    This builds a dict with the minimal information needed to operate as a
    valid IPython user namespace, which you can pass to the various embedding
    classes in ipython.
    """

    if user_ns is None:
        # Set __name__ to __main__ to better match the behavior of the
        # normal interpreter.
        user_ns = {'__name__'     :'__main__',
                   '__builtins__' : __builtin__,
                   }
    else:
        user_ns.setdefault('__name__','__main__')
        user_ns.setdefault('__builtins__',__builtin__)

    return user_ns


def make_user_global_ns(ns = None):
    """Return a valid user global namespace.

    Similar to make_user_ns(), but global namespaces are really only needed in
    embedded applications, where there is a distinction between the user's
    interactive namespace and the global one where ipython is running."""

    if ns is None: ns = {}
    return ns


def make_session(user_ns = None):
    """Makes, but does not launch an IPython session.
    
    Later on you can call obj.mainloop() on the returned object.

    Inputs:

      - user_ns(None): a dict to be used as the user's namespace with initial
      data.
    
    WARNING: This should *not* be run when a session exists already."""

    import IPython
    return IPython.Shell.start(user_ns)