class JIT:
'''
JIT is a class for Just In Time instantiation of objects. Init is called
only when the first attribute is either get or set.
'''
def __init__(self, klass, *args, **kw):
'''
klass -- Class of objet to be instantiated
*args -- arguments to be used when instantiating object
**kw -- keywords to be used when instantiating object
'''
self.__dict__['klass'] = klass
self.__dict__['args'] = args
self.__dict__['kw'] = kw
self.__dict__['obj'] = None
def initObj(self):
'''
Instantiate object if not already done
'''
if self.obj is None:
self.__dict__['obj'] = self.klass(*self.args, **self.kw)
def __getattr__(self, name):
self.initObj()
return getattr(self.obj, name)
def __setattr__(self, name, value):
self.initObj()
setattr(self.obj, name, value)
class TestIt:
def __init__(self, arg, keyword=None):
print 'In TestIt.__init__() -- arg: %s, keyword=%s' % (arg, keyword)
def method(self):
print 'In TestIt.method().'
def oldWay():
# Create t whether or not it gets used.
t = TestIt('The Argument', keyword='The Keyword')
def main():
# JIT refactored
t = JIT(TestIt, 'The Argument', keyword='The Keyword')
print 'Not intstaintiated yet.'
# TestIt object instantiated here.
t.method()
if __name__ == '__main__':
main()
# OUTPUT:
# Not intstaintiated yet.
# In TestIt.__init__() -- arg: The Argument, keyword=The Keyword
# In TestIt.method().
