how to control formatting of a namedtuple in a list

Boylan, Ross Ross.Boylan at ucsf.edu
Thu Nov 17 18:49:44 EST 2016


Thank you; I can confirm that overriding __repr__ makes the list display as I wanted.

The decision to use repr inside the list seems very odd, given the context, namely formatting something for display or looking for a simple string representation.  It seems more natural to me to use str or, if in a format, the default formatting all the way down.  Is there a good reason it's repr?

Ross
________________________________________
From: Python-list [python-list-bounces+ross.boylan=ucsf.edu at python.org] on behalf of Chris Angelico [rosuav at gmail.com]
Sent: Thursday, November 17, 2016 3:24 PM
To: python-list at python.org
Subject: Re: how to control formatting of a namedtuple in a list

On Fri, Nov 18, 2016 at 10:04 AM, Boylan, Ross <Ross.Boylan at ucsf.edu> wrote:
> Even after defining custom __str__ and __format__ methods they don't affect the display of objects when they are in a list.  Is there a way to change that, other than explicitly converting each list element to a string?
>

Yep! Inside a list, it's the repr that gets shown. So you should be
able to do this:

class Foo(namedtuple("Foo", "x")):
    def __repr__(self):
          return "foolish({})".format(self.x)

This will also affect the other forms - if you don't define __str__,
it'll use __repr__. So this should be all you need.

ChrisA
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