IPython/hooks.py

"""hooks for IPython.

In Python, it is possible to overwrite any method of any object if you really
want to.  But IPython exposes a few 'hooks', methods which are _designed_ to
be overwritten by users for customization purposes.  This module defines the
default versions of all such hooks, which get used by IPython if not
overridden by the user.

hooks are simple functions, but they should be declared with 'self' as their
first argument, because when activated they are registered into IPython as
instance methods.  The self argument will be the IPython running instance
itself, so hooks have full access to the entire IPython object.

If you wish to define a new hook and activate it, you need to put the
necessary code into a python file which can be either imported or execfile()'d
from within your ipythonrc configuration.

For example, suppose that you have a module called 'myiphooks' in your
PYTHONPATH, which contains the following definition:

import os
def calljed(self,filename, linenum):
    "My editor hook calls the jed editor directly."
    print "Calling my own editor, jed ..."
    os.system('jed +%d %s' % (linenum,filename))

You can then execute the following line of code to make it the new IPython
editor hook, after having imported 'myiphooks':

ip_set_hook('editor',myiphooks.calljed)

The ip_set_hook function is put by IPython into the builtin namespace, so it
is always available from all running code.

$Id: hooks.py 1019 2006-01-14 13:02:12Z vivainio $"""

#*****************************************************************************
#       Copyright (C) 2005 Fernando Perez. <[e-mail]>
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#*****************************************************************************

from IPython import Release
__author__  = '%s <%s>' % Release.authors['Fernando']
__license__ = Release.license
__version__ = Release.version

import os,bisect

# List here all the default hooks.  For now it's just the editor functions
# but over time we'll move here all the public API for user-accessible things.
__all__ = ['editor', 'fix_error_editor']

def editor(self,filename, linenum=None):
    """Open the default editor at the given filename and linenumber.

    This is IPython's default editor hook, you can use it as an example to
    write your own modified one.  To set your own editor function as the
    new editor hook, call ip_set_hook('editor',yourfunc)."""

    # IPython configures a default editor at startup by reading $EDITOR from
    # the environment, and falling back on vi (unix) or notepad (win32).
    editor = self.rc.editor
    
    # marker for at which line to open the file (for existing objects)
    if linenum is None or editor=='notepad':
        linemark = ''
    else:
        linemark = '+%d' % linenum
    # Call the actual editor
    os.system('%s %s %s' % (editor,linemark,filename))

import tempfile
def fix_error_editor(self,filename,linenum,column,msg):
    """Open the editor at the given filename, linenumber, column and 
    show an error message. This is used for correcting syntax errors.
    The current implementation only has special support for the VIM editor,
    and falls back on the 'editor' hook if VIM is not used.

    Call ip_set_hook('fix_error_editor',youfunc) to use your own function,
    """
    def vim_quickfix_file():
        t = tempfile.NamedTemporaryFile()
        t.write('%s:%d:%d:%s\n' % (filename,linenum,column,msg))
        t.flush()
        return t
    if os.path.basename(self.rc.editor) != 'vim':
        self.hooks.editor(filename,linenum)
        return
    t = vim_quickfix_file()
    try:
        os.system('vim --cmd "set errorformat=%f:%l:%c:%m" -q ' + t.name)
    finally:
        t.close()

class TryNext(Exception):
    pass

class CommandChainDispatcher:
    """ Dispatch calls to a chain of commands until some func can handle it
    
    Usage: instantiate, execute "add" to add commands (with optional
    priority), execute normally via f() calling mechanism.
    
    """
    def __init__(self,commands=None):
        if commands is None:
            self.chain = []
        else:
            self.chain = commands
            
            
    def __call__(self,*args, **kw):
        """ Command chain is called just like normal func. 
        
        This will call all funcs in chain with the same args as were given to this
        function, and return the result of first func that didn't raise
        TryNext """
        
        for prio,cmd in self.chain:
            #print "prio",prio,"cmd",cmd #dbg
            try:
                ret = cmd(*args, **kw)
                return ret
            except TryNext:
                pass
                
    def __str__(self):
        return str(self.chain)
    
    def add(self, func, priority=0):
        """ Add a func to the cmd chain with given priority """
        bisect.insort(self.chain,(priority,func))