extensions: load and configure extensions in well-defined phases

Extensions are now loaded with a call-graph like this:

  dispatch._dispatch
      extensions.loadall
          extensions.load
                # add foo module to extensions._extensions
          extensions.load
                # add bar module to extensions._extensions

          foo.uisetup(ui)
          bar.uisetup(ui)

      foo.extsetup()
      bar.extsetup()

      commands.table.update(foo.cmdtable)
      commands.table.update(bar.cmdtable)

  hg.repository
      foo.reposetup(ui, repo)
      bar.reposetup(ui, repo)

The uisetup calls could easily be moved out to dispatch._dispatch, but
have been kept in extensions.loadall since at least TortoiseHg calls
extensions.loadall and expects it to call uisetup.

The extensions.load function called uisetup. It now has an unused ui
argument which has been kept for backwards compatibility.

mercurial/dispatch.py

@@ -349,19 +349,20 b' def _dispatch(ui, args):'
         lui = ui.copy()
         lui.readconfig(os.path.join(path, ".hg", "hgrc"))
 
+    # Configure extensions in phases: uisetup, extsetup, cmdtable, and
+    # reposetup. Programs like TortoiseHg will call _dispatch several
+    # times so we keep track of configured extensions in _loaded.
     extensions.loadall(lui)
-    for name, module in extensions.extensions():
-        if name in _loaded:
-            continue
+    exts = [ext for ext in extensions.extensions() if ext[0] not in _loaded]
 
-        # setup extensions
-        # TODO this should be generalized to scheme, where extensions can
-        #      redepend on other extensions.  then we should toposort them, and
-        #      do initialization in correct order
+    # (uisetup is handled in extensions.loadall)
+
+    for name, module in exts:
         extsetup = getattr(module, 'extsetup', None)
         if extsetup:
             extsetup()
 
+    for name, module in exts:
         cmdtable = getattr(module, 'cmdtable', {})
         overrides = [cmd for cmd in cmdtable if cmd in commands.table]
         if overrides:
@@ -370,6 +371,8 b' def _dispatch(ui, args):'
         commands.table.update(cmdtable)
         _loaded.add(name)
 
+    # (reposetup is handled in hg.repository)
+
     addaliases(lui, commands.table)
 
     # check for fallback encoding

mercurial/extensions.py

@@ -40,6 +40,7 b' def loadpath(path, module_name):'
         return imp.load_source(module_name, path)
 
 def load(ui, name, path):
+    # unused ui argument kept for backwards compatibility
     if name.startswith('hgext.') or name.startswith('hgext/'):
         shortname = name[6:]
     else:
@@ -66,12 +67,9 b' def load(ui, name, path):'
     _extensions[shortname] = mod
     _order.append(shortname)
 
-    uisetup = getattr(mod, 'uisetup', None)
-    if uisetup:
-        uisetup(ui)
-
 def loadall(ui):
     result = ui.configitems("extensions")
+    newindex = len(_order)
     for (name, path) in result:
         if path:
             if path[0] == '!':
@@ -90,6 +88,11 b' def loadall(ui):'
             if ui.traceback():
                 return 1
 
+    for name in _order[newindex:]:
+        uisetup = getattr(_extensions[name], 'uisetup', None)
+        if uisetup:
+            uisetup(ui)
+
 def wrapcommand(table, command, wrapper):
     aliases, entry = cmdutil.findcmd(command, table)
     for alias, e in table.iteritems():

tests/test-extension

@@ -55,6 +55,29 b' cd a'
 hg foo
 echo 'barfoo = !' >> $HGRCPATH
 
+# check that extensions are loaded in phases
+cat > foo.py <<EOF
+import os
+name = os.path.basename(__file__).rsplit('.', 1)[0]
+print "1) %s imported" % name
+def uisetup(ui):
+    print "2) %s uisetup" % name
+def extsetup():
+    print "3) %s extsetup" % name
+def reposetup(ui, repo):
+    print "4) %s reposetup" % name
+EOF
+
+cp foo.py bar.py
+echo 'foo = foo.py' >> $HGRCPATH
+echo 'bar = bar.py' >> $HGRCPATH
+
+# command with no output, we just want to see the extensions loaded
+hg paths
+
+echo 'foo = !' >> $HGRCPATH
+echo 'bar = !' >> $HGRCPATH
+
 cd ..
 cat > empty.py <<EOF
 '''empty cmdtable

tests/test-extension.out

@@ -16,6 +16,14 b' uisetup called'
 reposetup called for a
 ui == repo.ui
 Foo
+1) foo imported
+1) bar imported
+2) foo uisetup
+2) bar uisetup
+3) foo extsetup
+3) bar extsetup
+4) foo reposetup
+4) bar reposetup
 empty extension - empty cmdtable
 
 no commands defined