environment/lib/python2.7/site-packages/IPython/utils/traitlets.py
def on_trait_change(self, handler, name=None, remove=False):
        """Setup a handler to be called when a trait changes.

        This is used to setup dynamic notifications of trait changes.

        Static handlers can be created by creating methods on a HasTraits
        subclass with the naming convention '_[traitname]_changed'.  Thus,
        to create static handler for the trait 'a', create the method
        _a_changed(self, name, old, new) (fewer arguments can be used, see
        below).

        Parameters
        ----------
        handler : callable
            A callable that is called when a trait changes.  Its
            signature can be handler(), handler(name), handler(name, new)
            or handler(name, old, new).
        name : list, str, None
            If None, the handler will apply to all traits.  If a list
            of str, handler will apply to all names in the list.  If a
            str, the handler will apply just to that name.
        remove : bool
            If False (the default), then install the handler.  If True
            then unintall it.
        """
        if remove:
            names = parse_notifier_name(name)
            for n in names:
                self._remove_notifiers(handler, n)
        else:
            names = parse_notifier_name(name)
            for n in names:
                self._add_notifiers(handler, n)
def on_trait_change(self, handler, name=None, remove=False):
        if remove:
            names = parse_notifier_name(name)
            for n in names:
                self._remove_notifiers(handler, n)
        else:
            names = parse_notifier_name(name)
            for n in names:
                self._add_notifiers(handler, n)
def on_trait_change ( self , handler , name = None , remove = False ) : if remove : names = parse_notifier_name ( name ) for n in names : self . _remove_notifiers ( handler , n ) else : names = parse_notifier_name ( name ) for n in names : self . _add_notifiers ( handler , n )
Setup a handler to be called when a trait changes.

        This is used to setup dynamic notifications of trait changes.

        Static handlers can be created by creating methods on a HasTraits
        subclass with the naming convention '_[traitname]_changed'.  Thus,
        to create static handler for the trait 'a', create the method
        _a_changed(self, name, old, new) (fewer arguments can be used, see
        below).

        Parameters
        ----------
        handler : callable
            A callable that is called when a trait changes.  Its
            signature can be handler(), handler(name), handler(name, new)
            or handler(name, old, new).
        name : list, str, None
            If None, the handler will apply to all traits.  If a list
            of str, handler will apply to all names in the list.  If a
            str, the handler will apply just to that name.
        remove : bool
            If False (the default), then install the handler.  If True
            then unintall it.
Setup a handler to be called when a trait changes .