realms-wiki/realms/lib/hook.py

74 lines
2 KiB
Python

from __future__ import absolute_import
from functools import wraps
from flask_sqlalchemy import DeclarativeMeta
def hook_func(name, fn):
@wraps(fn)
def wrapper(self, *args, **kwargs):
for hook, a, kw in self.__class__._pre_hooks.get(name) or []:
hook(self, *args, **kwargs)
rv = fn(self, *args, **kwargs)
# Attach return value for post hooks
kwargs.update(dict(rv=rv))
for hook, a, kw in self.__class__._post_hooks.get(name) or []:
hook(self, *args, **kwargs)
return rv
return wrapper
class HookMixinMeta(type):
def __new__(cls, name, bases, attrs):
super_new = super(HookMixinMeta, cls).__new__
hookable = []
for key, value in attrs.items():
# Disallow hooking methods which start with an underscore (allow __init__ etc. still)
if key.startswith('_') and not key.startswith('__'):
continue
if callable(value):
attrs[key] = hook_func(key, value)
hookable.append(key)
attrs['_hookable'] = hookable
return super_new(cls, name, bases, attrs)
class HookMixin(object):
__metaclass__ = HookMixinMeta
_pre_hooks = {}
_post_hooks = {}
_hookable = []
@classmethod
def after(cls, method_name):
assert method_name in cls._hookable, "'%s' not a hookable method of '%s'" % (method_name, cls.__name__)
def outer(f, *args, **kwargs):
cls._post_hooks.setdefault(method_name, []).append((f, args, kwargs))
return f
return outer
@classmethod
def before(cls, method_name):
assert method_name in cls._hookable, "'%s' not a hookable method of '%s'" % (method_name, cls.__name__)
def outer(f, *args, **kwargs):
cls._pre_hooks.setdefault(method_name, []).append((f, args, kwargs))
return f
return outer
class HookModelMeta(DeclarativeMeta, HookMixinMeta):
pass