From: Justin Frankel <justin@cockos•com>
To: Junio C Hamano <gitster@pobox•com>
Cc: Bert Wesarg <bert.wesarg@googlemail•com>,
Jonathan Nieder <jrnieder@gmail•com>,
git@vger•kernel.org, eyvind.bernhardsen@gmail•com
Subject: Re: [PATCH v2] git-merge: ignore space support
Date: Wed, 25 Aug 2010 11:21:02 -0700 [thread overview]
Message-ID: <4C755F0E.5080705@cockos.com> (raw)
In-Reply-To: <7vy6bushjx.fsf@alter.siamese.dyndns.org>
Junio C Hamano wrote:
> Justin Frankel <justin@cockos•com> writes:
>
>
>> The only danger is that ll_merge()'s signature didn't change in such a
>> way to break compilation, i.e:
>>
>> int ll_merge(mmbuffer_t *result_buf,
>> const char *path,
>> mmfile_t *ancestor, const char *ancestor_label,
>> mmfile_t *ours, const char *our_label,
>> mmfile_t *theirs, const char *their_label,
>> int flag);
>>
>> becomes:
>>
>> int ll_merge(mmbuffer_t *result_buf,
>> const char *path,
>> mmfile_t *ancestor, const char *ancestor_label,
>> mmfile_t *ours, const char *our_label,
>> mmfile_t *theirs, const char *their_label,
>> struct whatever *conf);
>>
>> In this case, passing 0 as the last parameter will compile either way.
>>
>> Sure, we can grep all of the source, but who knows when something else
>> will get merged in...
>>
>
> That is technically a valid concern but I suspect it does not matter in
> this particular case, where integer 0 used to mean "use the default" and
> the new API uses NULL to mean the same.
>
> If an existing call site used to pass 0 and the patch forgot to update it,
> it will look ugly (we encourage to spell a NULL pointer "NULL", not "0",
> in our codebase) but no harm is done. If an existing call site asked for
> a non-default behaviour by passing a non-zero integer flag, and the patch
> forgot to update it, the compiler would have caught it. Merging a side
> branch is the same deal; if it adds a call with a non-zero argument to ask
> for a non-default behaviour, that will be done via an expression over some
> integer variables or constants, and that won't be casted silently to a
> pointer to "struct whatever", no?
>
>
Agreed, I was responding to Bert's email, in which he stated that he
hadn't seen NULL-for-default anywhere else in git. Using NULL for
default behavior is good in that it handles un-updated code and merges
correctly (passing 0 uses defaults, passing nonzero fails compile).
> --
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>
next prev parent reply other threads:[~2010-08-25 18:21 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-23 20:59 [PATCH v2] git-merge: ignore space support Justin Frankel
2010-08-24 2:28 ` Jonathan Nieder
2010-08-24 3:39 ` [RFC/PATCH jn/merge-renormalize] merge-recursive: expose merge options for builtin merge Jonathan Nieder
2010-08-24 18:52 ` Junio C Hamano
2010-08-25 4:29 ` Jonathan Nieder
2010-08-24 4:30 ` [PATCH v2] git-merge: ignore space support Justin Frankel
2010-08-25 4:40 ` Jonathan Nieder
2010-08-25 7:22 ` Bert Wesarg
2010-08-25 15:51 ` Justin Frankel
2010-08-25 17:55 ` Junio C Hamano
2010-08-25 18:21 ` Justin Frankel [this message]
2010-08-24 19:01 ` Junio C Hamano
2010-08-24 20:01 ` Bert Wesarg
2010-08-25 3:57 ` Jonathan Nieder
2010-08-26 5:41 ` [PATCH v3 0/4] " Jonathan Nieder
2010-08-26 5:47 ` [PATCH 1/4] merge-recursive: expose merge options for builtin merge Jonathan Nieder
2010-08-26 5:49 ` [PATCH 2/4] ll-merge: replace flag argument with options struct Jonathan Nieder
2010-08-26 16:39 ` Junio C Hamano
2011-01-16 1:08 ` [PATCH v1.7.4-rc2] ll-merge: simplify opts == NULL case Jonathan Nieder
2010-08-26 5:50 ` [PATCH 3/4] merge-recursive --patience Jonathan Nieder
2010-08-26 5:51 ` [PATCH 4/4] merge-recursive: options to ignore whitespace changes Jonathan Nieder
2010-08-26 16:39 ` Junio C Hamano
2010-08-27 8:24 ` Jonathan Nieder
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