Ideas/MachineReadableFormats

Questions

  1. Goal: conceptual integrity across formats (eg. all formats use XML)
  2. Goal: avoid ad-hoc formats (eg. use XML or YAML if possible)
  3. Goal: use community standards for revision control if possible
  4. Do we want to use a single format for context files and changes –xml?
  5. The changes –match problem

Insights

  • annotate is a sort of special case, so we should give up on trying to achieve #1 for it
  • diff already uses community-based format (unified diff), so it would be silly to try to achieve #1 (conceptual integrity) at the expense of (#3)

We need a line-based format

There are two things that make markup-based formats problematic:

  • escaping markup characters
  • encoding arbitrary bytes - doable but ugly

Using a line-based format avoids these two problems because

  • the only markup character is newline, but for revision control systems, newlines by definition DO NOT EXIST (if you see a newline then you have a new line)

  • line-based format does not pretend to be text; it’s just bytes

TODO: trivial to parse

Tasks that 3rd party tools would want

  • File history (F)
  • Show patch (D)
  • Annotate (A)
  • Last touching patch (quickly!) (L)
  • Searching by metadata (S)

PRESENT formats

  • annotate XML (A)
  • changes XML (F,M,L)
  • changes -s XML (F,M,L)
  • diff (D)
  • annotate -p (D)
  • whatsnew (D)
  • whatsnew -s
  • changes -s
  • context files and patch bundles

FUTURE formats

We will converge on 4 formats

  1. unified diff format [SAME]
  2. line-separated annotate format [NEW! (adventure)] TODO: make sure we have a story for annotate directory
  3. patch disk format (taking eg. replace into account) [SAME]
  4. hashed context file format [NEW!]

    • basically a hashed version of current context file format [issue1550]
    • single field which tells if it’s valid context file (contains dependencies or not), so that we can safely use it for darcs changes –match (without risking the depless output being for get –context)

Note!

  • changes –xml will be deprecated in favour of #4
  • we will provide documentation for all the formats we create

Potentially open questions

  • annotate directory
  • pull –dry-run
  • git-gi
  • patch -> cached file version