support hooks written in python. to write hook in python, create module with hook function inside. make sure mercurial can import module (put it in $PYTHONPATH or load it as extension). hook function should look like this: def myhook(ui, repo, hooktype, **kwargs): if hook_passes: return True elif hook_explicitly_fails: return False elif some_other_failure: import util raise util.Abort('helpful failure message') else: return # implicit return of None makes hook fail! then in .hgrc, add hook with "python:" prefix: [hooks] commit = python:mymodule.myhook