[IPython-user] Controlling ipython prompt behavior

Robert Kern robert.kern at gmail.com
Wed Jun 14 14:12:11 CDT 2006

Tom Denniston wrote:
> When you hit enter at an Ipython prompt it prints out the repr of the
> results of evaluating the line.  Is there a way to override this
> behavior to control what gets done.  I could change the reprs on all
> my objects but that is not a great solution.

Yes. You can provide a 'result_display' function as a hook. I'm not sure what
the best way to access hooks is, but something like the following should work:

from IPython.genutils import Term
from IPython.hooks import result_display

def my_result_display(self, arg):
    """ Yes, self is needed here.

    See result_display() in IPython/hooks.py

    if type(arg) is MySpecialType:
        print >>Term.cout, arg.special_repr()
        # Fall back on the default behaviour.
        result_display(self, arg)
    return None

# Is there a better way to get the InteractiveShell instance besides __IP?
__IP.set_hook('result_display', my_result_display)

AFAICT, this *overrides* the current hook (unless if there is one of greater
priority, see InteractiveShell.set_hook() in IPython/iplib.py), so be sure that
your function can handle anything.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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