logtoprocess: extract logger class from ui wrapper

It provides the same interface as the blackboxlogger. The ui wrapper will
be removed shortly.

hgext/logtoprocess.py

@@ -38,6 +38,7 b' import os'
 
 from mercurial import (
     pycompat,
+    util,
 )
 from mercurial.utils import (
     procutil,
@@ -49,17 +50,22 b' from mercurial.utils import ('
 # leave the attribute unspecified.
 testedwith = 'ships-with-hg-core'
 
-def uisetup(ui):
-
-    class logtoprocessui(ui.__class__):
-        def log(self, event, *msg, **opts):
+class processlogger(object):
             """Map log events to external commands
 
             Arguments are passed on as environment variables.
+    """
 
-            """
-            script = self.config('logtoprocess', event)
-            if script:
+    def __init__(self, ui):
+        self._scripts = dict(ui.configitems(b'logtoprocess'))
+
+    def tracked(self, event):
+        return bool(self._scripts.get(event))
+
+    def log(self, ui, event, msg, opts):
+        script = self._scripts.get(event)
+        if not script:
+            return
                 env = {
                     b'EVENT': event,
                     b'HGPID': os.getpid(),
@@ -70,6 +76,24 b' def uisetup(ui):'
                            for key, value in pycompat.byteskwargs(opts).items())
                 fullenv = procutil.shellenviron(env)
                 procutil.runbgcommand(script, fullenv, shell=True)
+
+def uisetup(ui):
+
+    class logtoprocessui(ui.__class__):
+        def __init__(self, src=None):
+            super(logtoprocessui, self).__init__(src)
+            if src and r'_ltplogger' in src.__dict__:
+                self._ltplogger = src._ltplogger
+
+        # trick to initialize logger after configuration is loaded, which
+        # can be replaced later with processlogger(ui) in uisetup(), where
+        # both user and repo configurations should be available.
+        @util.propertycache
+        def _ltplogger(self):
+            return processlogger(self)
+
+        def log(self, event, *msg, **opts):
+            self._ltplogger.log(self, event, msg, opts)
             return super(logtoprocessui, self).log(event, *msg, **opts)
 
     # Replace the class for this instance and all clones created from it: