While working on issue58, I tried out the new "DARCS_PATCHES" export for
--posthook, which is in a plain-text format. That experience clarified for me
that we should also export DARCS_PATCHES_XML, providing the same data in XML
format. 

The reason is --posthook primarily exists for automation, and the XML format is
convenient for being processed by automated tools. By contract, parsing the
human-readable format of DARCS_PATCHES is cumbersome and hackish, requiring
things like matching lines that start with " * " to mean that we've found a
patch name.

Implemented.

Thanks David. 

This needs a small touch up. A wrapper XML element is missing, leaving a stream
of <patches> tags, which are not as easily parsed. 

I suggest either re-using <changelog> for consistency with "darcs changes", or
just "patches". 

Here's what the code looks like for "darcs changes":

         text "<changelog>"
      $$ vcat xml_file_names
      $$ vcat actual_xml_changes
      $$ text "</changelog>"

I'm not clear the difference between the meaning of "$" and "$$", so I'm not
going to attempt the fix myself right now. 

I've continued to work the updated roundup/darcs integration tonight.

Also, from reading the code it looks like these environment variables are not
set on Win32. Do we need to document that this part of --posthook doesn't work
on Win32, then?

  Mark

Just because I can't resist a chance to explain Haskell's weird syntax...

The $ operator is a standard Haskell operator that is really just a trick to
avoid extra parens (thus escaping from the lisp syndrome), so

(foo (bar (baz x))) is the same as foo $ bar $ baz x

The $$ operator is in fact unrelated to $ (except that they both are composed
entirely of the character '$'), and is a pretty-printer combinator that is
motivated by the regex '$', which indicates "separate these two things by a
newline.  We like using our pretty-printer because it allows tricks like
displaying in color on a terminal, but not when writing to a file or a pipe.

David

(Who is also sending a patch that will close this bug, hopefully...)

Okay, the new roundup hook didn't get this one, due to a weirdness of the exim
configuration on darcs.net.  But it works now.