Re: Google Summer of Code 2009: GIT

> On Fri, 13 Mar 2009, saurabh gupta wrote:
>
> defining terminology that was mentioned before
>
> merge drivers are run by git to do the merges and create the conflict
> markers. git already has a 'plug-in architecture' for these drivers (you can
> define file types and tell git to use a particular merge driver for this
> file type)
>
> merge helpers are run by the users if there is a conflict and make use of
> the markers. depending on what you end up using for conflict markers, you
> may not need to write a merge helper (for OO, if your conflict markers are
> good enough you can use OO to resolve conflicts easily, no need for a new
> tool)
>
>
> with this terminology, you can't do merge helpers without doing the merge
> drivers first (what does the helper look for as an indicator of a conflict?)
>
> I believe that there is a lot of potential for a configurable merge driver
> to support many similar formats.
>
> using the example of XML-based files, configurable options could include
>
> 1. is the file stored compressed or not
>
> 2. does the order of the tags matter
>
> 3. does whitespace matter
>
>  note: #2 and #3 may boil down to 'is this a document with XML markup, or
> are the XML tags the primary content'
>
> 4. how is the conflict marked
>
> 4a. wrap the conflicting tags in a set of tags that look like _
>
> 4b. if the conflict is in the content, not the tags, modify it similar to
> what we do with text today.
>
>  note: this still requires the new driver to decide if there is a conflict
> or not
>
> 4c. other (potentially including calling out to other code for more drastic
> restructuring)
>
>
> with a merge driver along these lines you can handle many different types of
> XML documents.
>
> with SVG you may be able to put the offending tags in different layers
>
> with OO you may be able to put in tags that indicate a merge conflict in a
> way that OO will directly handle
>
> etc.
>
> in many cases you may not even need to create a merge helper or library for
> other software you use. you just need to figure out what sort of
> manipulation would need to be done to to file to mark the conflict in a way
> that existing applications can understand.