Re: [PATCH 1/7] strbuf: add "include_delim" parameter to "strbuf_split"

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 13, 2009, 07:06 UTC
Message-ID: <7v7i2tj411.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <200903130702.01039.chriscool@tuxfamily.org>

Christian Couder <chriscool@tuxfamily.org> writes:

Show 7 quoted lines

>> Also comparing this with Perl/Python split() forgets that you are working
>> in C, where truncating an existing string is quite cheap (just assign
>> '\0'). There is a different trade-off to be made in these language
>> environments.
>
> Sorry but I think the goal of the strbuf API is to be quite high level, so I 
> think comparing this with Perl/Python is ok.

I think you are mistaken again.

The highlevel-ness of strbuf holds true only while you live in the strbuf world, but you should consider what happens when its end product finally gets used in the calling function written in C. It will be a good-old NUL terminated string or just a chunk of memory with known length.

For a user written in C, it is far easier and cheaper to trim excess at the end, especially when the length of the string is known (strbuf_detach gives you the length of the string exactly for this reason) than having to extend it (in order to recover the lost delimiter because the splitter removed it). Trimming from the front is also cheap (just move the head pointer and start consuming from the middle).