Re: ChangeLogs

[Jaroslav Hajek]

On Wed, Mar 17, 2010 at 2:07 AM, Rik <address@hidden> wrote:
>
>>>
>> What happened to the plan (or was it a plan already?) to move the ChangeLog
>> entries into the mercurial commit messages?
> This seems like a very good idea.

Well, as has been pointed out previously, it has some negative
effects. In particular we'd lose the advantage of having the related
changelogs grouped per directory.

> One of the current complications with
> using a non-linear commit strategy is that everyone touches the same file,
> ChangeLog, on every commit.  This leads Mercurial into attempting an
> unnecessary 3-way merge of that file whenever a personal repository is
> pushed back to the main repository.
>
> --Rik
>

I made the following modification to my Mercurial to combat this
problem (may require a trivial merge in the import section if the
parent is outdated):

# HG changeset patch
# User Jaroslav Hajek <address@hidden>
# Date 1264432918 -3600
# Node ID 436f14ca18e80ba8c72a22a106eccdc366782d61
# Parent  f68eaaf6891032750d26ea989607983a297806c3
allow smart treatment of GNU-style ChangeLog files

diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -41,6 +41,7 @@
         'ignorewsamount': False,
         'ignoreblanklines': False,
         'upgrade': False,
+        'changelogmask': False,
         }

     __slots__ = defaults.keys()
diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -10,7 +10,7 @@
 from node import hex, nullid, short
 import base85, cmdutil, mdiff, util, diffhelpers, copies
 import cStringIO, email.Parser, os, re
-import sys, tempfile, zlib
+import sys, tempfile, zlib, fnmatch

 gitre = re.compile('diff --git a/(.*) b/(.*)')

@@ -1065,6 +1065,7 @@
         ignorews=get('ignore_all_space', 'ignorews'),
         ignorewsamount=get('ignore_space_change', 'ignorewsamount'),
         ignoreblanklines=get('ignore_blank_lines', 'ignoreblanklines'),
+        changelogmask=get('changelog_mask', 'changelogmask', getter=ui.config),
         context=get('unified', getter=ui.config))

 def updatedir(ui, repo, patches, similarity=0):
@@ -1415,6 +1416,19 @@
             if dodiff == 'binary':
                 text = b85diff(to, tn)
             else:
+               # check whether this can be a ChangeLog entry
+               ischangelogentry = False
+               if (a == b and opts.changelogmask
+                   and fnmatch.fnmatch(a, opts.changelogmask)):
+                   lto = len(to)
+                   ltn = len(tn)
+                   if ltn > lto and tn[-lto:] == to and tn[-lto-1] == '\n':
+                       ischangelogentry = True
+               # if so, strip the rest of the file to get only the prepended
+               # lines dumped
+               if ischangelogentry:
+                   tn = tn[:-lto]
+                   to = ''
                 text = mdiff.unidiff(to, date1,
                                     # ctx2 date may be dynamic
                                     tn, util.datestr(ctx2.date()),


with this patch, I can set

changelogmask=*ChangeLog

in my .hgrc to force mercurial generate a context-free diff for
ChangeLogs, if a hunk of text is only prepended to them. Together with
the mq extension, this eliminates 99% of problems with ChangeLogs,
because the context-free diffs re-apply smoothly in any order. This
also works well for transplanting (which was actually the reason I did
it).

-- 
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz