Peg revisions

[Martin Pool]

On 9 February 2011 20:44, Eric Siegerman <lists08-bzr at davor.org> wrote:
> On Tue, 2011-02-08 at 20:03 -0600, John Arbash Meinel wrote:
>> I'm guessing [--name-from-revision] was added to force looking in the
> revision before
>> the working tree.
>
> This seems like an ad-hoc attempt at Subversion's concept of "peg
> revisions".  I've thought for some time that Bazaar could benefit
> from the same idea, but have hesitated to suggest it because it
> would entail a pretty thorough going-over of many (most?) of the
> command syntaxes.  Since such a going-over seems to be in the
> process of being born, though, now's the time :-)
>
> Subversion distinguishes between what they call "peg" and
> "operative" revisions.  The latter are what svn and bzr both mean
> by "-rREV", i.e. the revision on which the command is supposed to
> operate (cat, merge from, revert to, whatever).
>
> One specifies a peg revision using the syntax "PATHNAME at PEG"; it
> means "the file that had name PATHNAME in revision PEG".  It is
> used *only* for what, in bzr terms, would be mapping the pathname
> to a file-id.  The gist is that:
>    svn cat -rOPER PATHNAME at PEG
> does (their equivalent of) this:
>  - maps (PATHNAME, PEG) to a FILE-ID
>  - cats revision OPER's version the file with id FILE-ID

Yes, that's pretty much what it is.  Perhaps we should simply adopt
the svn syntax and/or name for it.