Enhanced dir() function

Tim Chase python.list at tim.thechases.com
Fri Jul 1 19:20:57 CEST 2011


On 06/30/2011 11:29 PM, Steven D'Aprano wrote:
> The dir() function is designed for interactive use, inspecting objects for
> the names of attributes and methods.
>
> Here is an enhanced version that allows you to pass a glob to filter the
> names you see:
>
> Comments and improvements welcome.

Having not seen any other comments on it fly by, I thought I'd 
respond.  While in general I like the idea, I'm not sure when I'd 
go to the effort of bringing the function into my namespace when 
I could just do something like

   >>> [s for s in dir(...) if test_of_interest(s)]

If it came in as an effortless (i.e. O(1) where I do it once and 
never again; not an O(n) where n=the number of times I invoke 
Python) default replacement for dir(), I'd reach for it a lot 
more readily.  I seem to recall there's some environment-var or 
magic file-name that gets sourced on every startup.

I use the list-comp version on a regular basis:

   # implementation of which magic methods?
   [s for s in dir(foo) if s.startswith('__') and s.endswith('__')]

   # ignore magic methods
   [s for s in dir(foo) if not (s.startswith('__') and 
s.endswith('__'))]

   # constants
   [s for s in dir(foo) if s.isupper()]

   # keywording
   [s for s in dir(foo) if 'bar' in s.lower()]

Anyways, even if it just includes a brief blurb about "and this 
is how you get it automatically in every Python session" (or a 
link to the docs on how to do that), it would raise it from "meh" 
to "nifty".

-tim





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