———-
class ScriptBase(object):
def __init__(self):
self._p = optparse.OptionParser()

self._p.add_option('–version', action='store_true',
help='Print the version and exit')

def set_parser_usage(self, usage):
self._p.set_usage(usage)

def pre_load_project_hook(self):
pass

def post_load_project_hook(self):
pass

def run():
self._options, self._args = self._p.parse_args()
if self.options.version:
print_version()
return
self.pre_load_project_hook()

pitzdir = Project.find_pitzdir(options.pitzdir)
self._proj = Project.from_pitzdir(pitzdir)
self._proj.find_me()

self.post_load_project_hook()
proj.save_entities_to_yaml_files()

# and a script inherits from it:

class PitzAttachFile(ScriptBase):
def __init__(self):
self.set_parser_usage(“%prog entity file-to-attach”)
def pre_load_project_hook(self):
if len(self._args) != 2:
self._p.print_usage()
return
def post_load_project_hook(self):
e, filepath = self._proj[args[0]], args[1]
e.save_attachment(filepath)

# and here we run the script:
pitz_attach_file = PitzAttachFile()
pitz_attach_file.run()

——-

Note that this is totally untested and written in the comment field, so indentation might be wrong etc., but I hope to get across what this is all about – it's a “script framework” (Hollywood-principle: Don't call us, we call you).

You can make a hook mandatory by raising a NotImplementedError in the base class.