context aware context decorator for maya

contextDecorator.py

#!/usr/bin/env python 

from abc import ABCMeta, abstractmethod
from functools import wraps
import time

class Singleton(ABCMeta):
    _instance = None

    def __call__(cls, *args, **kwargs):
        if not hasattr(cls, "_instance") or cls._instance is None:
            cls._instance = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instance


class ContextDecorator(object):

    __metaclass__ = Singleton

    def __init__(self, *args, **kwargs):
        self.args = args
        self.__dict__.update(kwargs)
        self._built = False
        self._contextExists = False
        self._rebuild = kwargs.get('rebuild', False)

    @abstractmethod
    def _build(self):
        pass

    @abstractmethod
    def _destroy(self):
        pass

    @classmethod
    def clear_singleton(cls):
        cls._instance = None

    def __enter__(self):
        if not self._built or self._rebuild:
            self._build()
            self._built = True
            print 'call _build first time'
        else:
            print 'skip _build'
            self._contextExists = True

        return self

    def __exit__(self, typ, val, traceback):
        if not self._contextExists or self._rebuild:
            self._destroy()
            self.clear_singleton()
            # self._contextExists=False
            print 'call _destroy first time'
        else:
            print 'skip _destroy'
            self._contextExists = False

    def __call__(self, f):
        self.function = f

        @wraps(f)
        def wrapper(*args, **kw):
            with self:
                try:
                    return f(*args, **kw)
                except:
                    raise
        return wrapper


class CustomContext(ContextDecorator):

    def __init__(self, *args, **kwargs):
        super(CustomContext, self).__init__(*args, **kwargs)

    def _build(self):
        pass

    def _destroy(self):
        pass




print 'context manager test'

with CustomContext():
    for i in range(3):
        with CustomContext():
            time.sleep(0.01)


print '-' * 10
print 'decorator test'


@CustomContext()
@CustomContext()
def test():
    print 'inside test func'


test()