> -----Original Message-----
> From: Julian Foad [mailto:julian.f...@wandisco.com]
> Sent: dinsdag 2 augustus 2011 15:59
> To: Subversion Development
> Subject: RFC: Improving the 'diff callbacks'
>
> I'm looking at rationalizing the way the client handles diffs, which is
> currently mostly through the "svn_wc_diff_callbacks4_t" interface, with
> some use made of svn_delta_editor_t. I'll loosely abbreviate symbol
> names below, for example "diff_callbacks_t" to refer to the former.
>
> In libsvn_client, currently:
>
> Diff what? Producer Interface Consumer
>
> Normal diff:
> repo-repo svn_ra_do_diff3 + |> diff_callbacks_t |> diff_callbacks
> get_diff_editor | | in diff.c;
> repo-wc svn_ra + svn_wc | | prints diff to
> wc-wc svn_wc_diff6 | | stdout
>
> Summarizing diff:
> repo-repo svn_ra_do_diff3 |> delta_editor_t |> repos_diff_
> | | summarize.c;
> | | calls sum-cb
> repo-wc not implemented
> wc-wc not implemented
>
> What's going on here? Why is the summarizing diff output subsystem not
> simply an alternative consumer to the normal diff? If it used the same
> interface, we should be able to plug it straight in.
>
> First I wondered why the delta_editor_t isn't a suitable interface for
> diffs, and why the WC defines its own 'callback' type for this. One
> reason is because we want a symmetric diff, one that provides the full
> content of both what's added and what's deleted. Although the
> summarizing diff doesn't need to know about file content or property
> deletions, it does want to know about file and directory deletions, so
> that would seem to be a good thing. So why aren't we using the
> diff_callbacks_t here?
Maybe because the diff callbacks transfer the full texts of both before and
after a change to provide them to the callback?
The summarize function might have been designed to reduce that overhead?
Bert
