Re: [PATCH 3/9] diff: avoid generating unused hunk header lines

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

>> to have *some* names there, for the sake of a
>> simply described coding style without many exceptions
>> (especially those exceptions that rely on judgement).
>
> Fair enough.

For the record, there aren't "many" exceptions to the rule that was
suggested earlier: if you refer to parameters by name in the comment
to explain the interface, name them and use these names [*1*].

> Squashable patch is below; it goes on 34c829621e (diff: avoid generating
> unused hunk header lines, 2018-11-02).
>
> Junio, let me know if you'd prefer a re-send of the series, but it
> doesn't look necessary otherwise (so far).

Giving them proper names would serve as a readily usable sample for
those who write new hunk-line callbacks that do not ignore them, so
what you wrote is good.  Let me squash it in.

Thanks.  If this were to add bunch of "unused$n" names to the
parameters to this no-op function, only to "have *some* names
there", I would have said that it is not even worth the time to
discuss it, though.

> diff --git a/xdiff-interface.h b/xdiff-interface.h
> index 7b0ccbdd1d..8af245eed9 100644
> --- a/xdiff-interface.h
> +++ b/xdiff-interface.h
> @@ -39,7 +39,9 @@ extern int git_xmerge_style;
>   * Can be used as a no-op hunk_fn for xdi_diff_outf(), since a NULL
>   * one just sends the hunk line to the line_fn callback).
>   */
> -void discard_hunk_line(void *, long, long, long, long, const char *, long);
> +void discard_hunk_line(void *priv,
> +		       long ob, long on, long nb, long nn,
> +		       const char *func, long funclen);
>  
>  /*
>   * Compare the strings l1 with l2 which are of size s1 and s2 respectively.
>
> -Peff

[Footnote]

*1* You may say that the "if you refer to parameters by name" part
relies on judgment, but I think it is a good thing---it makes poor
judgment stand out.

When describing a function that takes two parameters of the same
type, for example, you could explain the interface as "take two ints
and return true if first int is smaller than the second int" in
order to leave the parameters unnamed, but if you gave such a
description, it is so obvious that you are _avoiding_ names.  Not
using names when you do not have to is good, but nobody with half an
intelligence would think it is good to give a bad description just
to avoid using names.