[PATCH 1 of 2] scmutil: improve documentation of revset APIs

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1466907140 25200
#      Sat Jun 25 19:12:20 2016 -0700
# Node ID 4903c4201049a504ed7ca47557a41a1c02e9391f
# Parent  fbe380dc227a0240939aa5a4941eda70d958ea40
scmutil: improve documentation of revset APIs

I can never remember the differences between the various revset
APIs. I can never remember that scmutil.revrange() is the one I
want to use from user-facing commands.

Add some documentation to clarify this.

While we're here, the argument name for revrange() is changed to
"specs" because that's what it actually is.

diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -549,28 +549,34 @@ class localrepository(object):
         return iter(self.changelog)
 
     def revs(self, expr, *args):
         '''Find revisions matching a revset.
 
         The revset is specified as a string ``expr`` that may contain
         %-formatting to escape certain types. See ``revset.formatspec``.
 
-        Return a revset.abstractsmartset, which is a list-like interface
+        Revset aliases from the configuration are not expanded. To expand
+        user aliases, consider calling ``scmutil.revrange()``.
+
+        Returns a revset.abstractsmartset, which is a list-like interface
         that contains integer revisions.
         '''
         expr = revset.formatspec(expr, *args)
         m = revset.match(None, expr)
         return m(self)
 
     def set(self, expr, *args):
         '''Find revisions matching a revset and emit changectx instances.
 
         This is a convenience wrapper around ``revs()`` that iterates the
         result and is a generator of changectx instances.
+
+        Revset aliases from the configuration are not expanded. To expand
+        user aliases, consider calling ``scmutil.revrange()``.
         '''
         for r in self.revs(expr, *args):
             yield self[r]
 
     def url(self):
         return 'file:' + self.root
 
     def hook(self, name, throw=False, **args):
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -803,20 +803,39 @@ def revpair(repo, revs):
         raise error.Abort(_('empty revision on one side of range'))
 
     # if top-level is range expression, the result must always be a pair
     if first == second and len(revs) == 1 and not _pairspec(revs[0]):
         return repo.lookup(first), None
 
     return repo.lookup(first), repo.lookup(second)
 
-def revrange(repo, revs):
-    """Yield revision as strings from a list of revision specifications."""
+def revrange(repo, specs):
+    """Execute 1 to many revsets and return the union.
+
+    This is the preferred mechanism for executing revsets using user-specified
+    config options, such as revset aliases.
+
+    The revsets specified by ``specs`` will be executed via a chained ``OR``
+    expression. If ``specs`` is empty, an empty result is returned.
+
+    ``specs`` can contain integers, in which case they are assumed to be
+    revision numbers.
+
+    It is assumed the revsets are already formatted. If you have arguments
+    that need to be expanded in the revset, call ``revset.formatspec()``
+    and pass the result as an element of ``specs``.
+
+    Specifying a single revset is allowed.
+
+    Returns a ``revset.abstractsmartset`` which is a list-like interface over
+    integer revisions.
+    """
     allspecs = []
-    for spec in revs:
+    for spec in specs:
         if isinstance(spec, int):
             spec = revset.formatspec('rev(%d)', spec)
         allspecs.append(spec)
     m = revset.matchany(repo.ui, allspecs, repo)
     return m(repo)
 
 def meaningfulparents(repo, ctx):
     """Return list of meaningful (or all if debug) parentrevs for rev.