On 2006-11-24, Junio C Hamano <junkio@cox.net> wrote:
quoted text
> Peter Baumann <Peter.B.Baumann@stud.informatik.uni-erlangen.de>
> writes:
>
>> One question, what's the difference between git-log -p and
>> git-whatchanged -p?
>> ...
>> As you can see, the root commit isn't shown. Is this intentional?
>
> Some historical background.
>
> The traditional command do do log-minded things was whatchanged
> and it was implemented as
>
> 	git rev-list $revision_args -- $path_limits |
>         git diff-tree --stdin --pretty -r $format_args
>
> and whatchanged did not give --root to diff-tree by default.
> And 'diff-tree' does not show --pretty logs when there is no
> diff to be shown (which still is true today and is a useful
> behaviour), hence no mention of the root commit.
>
> On the other hand, "git-log" traditionally looked like this:
>
> 	git rev-list --pretty $revision_args 
>
> Back then, there was no path_limits nor even diff options to
> it.
>
> Later, Linus (with help from others) made the revision walk
> machinery as callable inside programs other than "rev-list",
> eliminating the need to pipe rev-list into diff-tree to perform
> log-minded things.  That enriched what "git log" can do, and
> mostly made "whatchanged" a redundant command.  As you may have
> noticed, there isn't much difference between these two commands
> in builtin-log.c; their differences are solely what default
> options for diff and revision machinery are used and are meant
> to match the traditional behaviour of these commands.
>
> So there shouldn't be any differences, really, when you override
> their defaults with the likes of -p.
>
> Honestly speaking, I do not think there was _any_ consciously
> designed intention to handle root commits, either to make these
> commands behave identically or differently; regarding parentless
> commits, they just behave the way they happen to behave, because
> root commits were not something either Linus nor I were
> interested in.
>
> Given the recent discussion, however, the intention now should
> be that Porcelain level commands should default to do --root
> (i.e.  when asked to do "diff" to show how a commit without a
> parent differs from its nonexistent parent, show diff with
> emptiness).
>

Ah. I see. Thanks for the clarification.

Peter

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