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[Augie Fackler]

On Jun 20, 2009, at 7:16 PM, Krzysiek Pawlik wrote:

>
> Hello,
>
> I was missing simple way of showing diff for specific revision, it  
> can be done
> with for example `hg diff -r 852:853' or `hg log -p -r 853' -- but  
> the first
> requires typing a lot of numbers and is error prone (especially when  
> repository
> hits revisions >=10000), the second one displays log entry which is  
> not needed
> when you're interested in diff only.

What's wrong with diff -c <revision>? That might be new since 1.2, but  
it's still already there without a special revision spec.

> I'm attaching a simple patch that adds a notion of previous  
> revision. It's
> denoted as ^<rev>, so above example becomes `hg diff -r ^853'. In  
> fact ^<rev> is
> expanded to revision range <rev - 1>:<rev>, this behaviour produces  
> *two*
> changesets in output for `hg log -r ^tip'. In case of ^0 an error is  
> generated,
> as revision 0 simply can't have previous revision.

This is an interesting idea, but that's somewhat confusing when you  
consider parentrevspec uses rev^ to mean the first parent of the  
revision.

> The change is in cmdutil.py file so any command that uses -r gains  
> this ability.

This feels like it belongs in an extension to me, but I've also got  
the previously mentioned concern about similarity to the existing  
parentrevspec extension.

> If there are no objections I'd like the patch be applied to main.
>
> -- 
> Krzysiek Pawlik (Nelchael)       GPG Key ID: 0xBC555551
>      http://www.linkedin.com/in/krzysiekpawlik
> # HG changeset patch
> # User Krzysiek Pawlik <krzysiek.pawlik at people.pl>
> # Date 1245541797 -3600
> # Node ID 2e78983c753740e1cba9ab2dcdc1e7290fc36ec1
> # Parent  91e26fb24fb154ca55953a3445c514c7819e1e6b
> Add ability to easily specify previous revision: prepend it with ^
>
> For example: ^tip - this means previous to tip and tip, so `hg log - 
> r ^tip' displays two changesets, `hg diff -r ^tip' shows diff from  
> previous to tip.
>
> diff -r 91e26fb24fb1 -r 2e78983c7537 mercurial/cmdutil.py
> --- a/mercurial/cmdutil.py	Thu Jun 18 16:56:03 2009 -0500
> +++ b/mercurial/cmdutil.py	Sun Jun 21 00:49:57 2009 +0100
> @@ -135,6 +135,10 @@ def revpair(repo, revs):
>             start, end = revs[0].split(revrangesep, 1)
>             start = revfix(repo, start, 0)
>             end = revfix(repo, end, len(repo) - 1)
> +        elif revs[0].startswith("^"):
> +            start, end = revrange(repo, [revs[0]])
> +            start = revfix(repo, start, 0)
> +            end = revfix(repo, end, len(repo) - 1)
>         else:
>             start = revfix(repo, revs[0], None)
>     elif len(revs) == 2:
> @@ -166,6 +170,16 @@ def revrange(repo, revs):
>                     continue
>                 seen.add(rev)
>                 l.append(rev)
> +        elif spec.startswith("^"):
> +            start = revfix(repo, spec[1:], 0) - 1
> +            end = revfix(repo, spec[1:], len(repo) - 1)
> +            if start == -1:
> +                raise util.Abort(_('revision %d has no parent') %  
> end)
> +            for rev in [start, end]:
> +                if rev in seen:
> +                    continue
> +                seen.add(rev)
> +                l.append(rev)
>         else:
>             rev = revfix(repo, spec, None)
>             if rev in seen:
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