Re: ordered string-list considered harmful, was Re: [PATCH v3] Allow aliases that include other aliases

From: Jeff King <peff@peff.net>
To: git@vger.kernel.org
Cc: Tim Schumacher <timschumi@gmx.de>, gitster@pobox.com, pclouds@gmail.com
Subject: Re: ordered string-list considered harmful, was Re: [PATCH v3] Allow aliases that include other aliases
Date: Thu, 6 Sep 2018 15:20:22 -0400	[thread overview]
Message-ID: <20180906192021.GB26575@sigill.intra.peff.net> (raw)
In-Reply-To: <20180906191203.GA26184@sigill.intra.peff.net>

On Thu, Sep 06, 2018 at 03:12:03PM -0400, Jeff King wrote:

> On Thu, Sep 06, 2018 at 10:59:42AM -0400, Jeff King wrote:
> 
> > > +		string_list_append(&cmd_list, *argv[0]);
> > 
> > This will create an unsorted list. You'd have to use
> > string_list_insert() here for a sorted list, or
> > unsorted_string_list_has_string() in the earlier call.
> > 
> > It's unfortunate that string_list makes this so easy to get wrong.
> 
> This is getting really off-topic (since it sounds like we'd probably
> want to use an ordered list here), but is it crazy to think that
> basically every use of an ordered string list could just be a hashmap?

Er, oops, I used "ordered" to mean two things here.

I meant that the code regarding aliases would use an _unsorted_ list
(where we care about keeping the original insertion order).

But what I think is harmful is a _sorted_ list, because of the
"accidentally quadratic" nature, and because it's easy to call its
functions on an unsorted list.

-Peff