diff hgext/histedit.py @ 27262:3d0feb2f978b

histedit: pick an appropriate base changeset by default (BC)

Previously, `hg histedit` required a revision argument specifying which
revision to use as the base for the current histedit operation. There
was an undocumented and experimental "histedit.defaultrev" option that
supported defining a single revision to be used if no argument is
passed.

Mercurial knows what changesets can be edited. And in most scenarios,
people want to edit this history of everything on the current head that
is rewritable. Making histedit do this by default and not require
an explicit argument or additional configuration is a major usability
win and will enable more people to use histedit.

This patch changes the behavior of the experimental and undocumented
"histedit.defaultrev" config option to select an appropriate base
revision by default. Comprehensive tests exercising the edge cases
in the new, somewhat complicated default revset have been added.
Surprisingly, no tests broke. I guess we were never testing the
behavior with no ANCESTOR argument (it used to fail with
"abort: histedit requires exactly one ancestor revision"). The new
behavior is much more user friendly.

The functionality for choosing the default base revision has been
moved to destutil.py, where it can easily be modified by extensions.

--- a/hgext/histedit.py	Sat Dec 05 23:50:13 2015 +0900
+++ b/hgext/histedit.py	Sat Oct 24 19:56:39 2015 +0100
@@ -149,6 +149,13 @@
 
   [histedit]
   linelen = 120      # truncate rule lines at 120 characters
+
+``hg histedit`` attempts to automatically choose an appropriate base
+revision to use. To change which base revision is used, define a
+revset in your configuration file::
+
+  [histedit]
+  defaultrev = only(.) & draft()
 """
 
 try:
@@ -166,6 +173,7 @@
 from mercurial import error
 from mercurial import copies
 from mercurial import context
+from mercurial import destutil
 from mercurial import exchange
 from mercurial import extensions
 from mercurial import hg
@@ -786,13 +794,19 @@
      ('f', 'force', False,
       _('force outgoing even for unrelated repositories')),
      ('r', 'rev', [], _('first revision to be edited'), _('REV'))],
-     _("ANCESTOR | --outgoing [URL]"))
+     _("[ANCESTOR] | --outgoing [URL]"))
 def histedit(ui, repo, *freeargs, **opts):
     """interactively edit changeset history
 
-    This command edits changesets between ANCESTOR and the parent of
+    This command edits changesets between an ANCESTOR and the parent of
     the working directory.
 
+    The value from the "histedit.defaultrev" config option is used as a
+    revset to select the base revision when ANCESTOR is not specified.
+    The first revision returned by the revset is used. By default, this
+    selects the editable history that is unique to the ancestry of the
+    working directory.
+
     With --outgoing, this edits changesets not found in the
     destination repository. If URL of the destination is omitted, the
     'default-push' (or 'default') path will be used.
@@ -917,10 +931,10 @@
         else:
             revs.extend(freeargs)
             if len(revs) == 0:
-                # experimental config: histedit.defaultrev
-                histeditdefault = ui.config('histedit', 'defaultrev')
-                if histeditdefault:
-                    revs.append(histeditdefault)
+                defaultrev = destutil.desthistedit(ui, repo)
+                if defaultrev is not None:
+                    revs.append(defaultrev)
+
             if len(revs) != 1:
                 raise error.Abort(
                     _('histedit requires exactly one ancestor revision'))