summary: augment output with info from extensions

mercurial/cmdutil.py

@@ -2082,3 +2082,6 b' def command(table):'
         return decorator
 
     return cmd
+
+# a list of (ui, repo) functions called by commands.summary
+summaryhooks = util.hooks()

mercurial/commands.py

@@ -5489,6 +5489,8 b' def summary(ui, repo, **opts):'
         ui.write(_('update: %d new changesets, %d branch heads (merge)\n') %
                  (new, len(bheads)))
 
+    cmdutil.summaryhooks(ui, repo)
+
     if opts.get('remote'):
         t = []
         source, branches = hg.parseurl(ui.expandpath('default'))

mercurial/util.py

@@ -1946,3 +1946,19 b' def sizetoint(s):'
         return int(t)
     except ValueError:
         raise error.ParseError(_("couldn't parse size: %s") % s)
+
+class hooks(object):
+    '''A collection of hook functions that can be used to extend a
+    function's behaviour. Hooks are called in lexicographic order,
+    based on the names of their sources.'''
+
+    def __init__(self):
+        self._hooks = []
+
+    def add(self, source, hook):
+        self._hooks.append((source, hook))
+
+    def __call__(self, *args):
+        self._hooks.sort(key=lambda x: x[0])
+        for source, hook in self._hooks:
+            hook(*args)