Re: [PATCH] merge: use string_list_split() in add_strategies()

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 8, 2016, 17:55 UTC
Message-ID: <xmqqeg5zf8mh.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <alpine.DEB.2.20.1608081034250.5786@virtualbox>

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

Show 9 quoted lines

> I wonder, however, if we could somhow turn things around by introducing
> something like
>
> 	split_and_do_for_each(item_p, length, string, delimiter)
> 		... <do something with item_p and length> ...
>
> that both string_list_split() *and* add_strategies() could use? We would
> then be able to avoid allocating the list and duplicating the items in the
> latter case.

I do think such a feature may be useful if we often work on pieces of a string delimited by a delimiter, but if the caller does not see the split result, then the function with "split" is probably misnamed.

I however suspect the variant of this where "delimiter" can just be a single byte would not be so useful.

If the input comes from the end user, we certainly would want to allow "word1 word2\tword3 " as input (i.e. squishing repeated delimiters into one without introducing an "empty" element, allowing more than one delimiter characters like SP and HT, and ignoring leading or trailing runs of delimiter characters).

If the input is generated internally, perhaps we should rethink the interface between the function that wants to do the for-each-word and its caller; if the caller wants to pass multiple things to the callee, it should be able to do so without first having to stuff these multiple things into a single string, only to force the callee to use this helper to split them out into individual pieces.