Quickly create flexible Python decorators
Python has a few forms for decorators, you can have a plain simple decorator, with no arguments:
@mydecorator def foo(): pass
Or a decorator with some arguments:
@mydecorator(1, 2) def foo(): pass
You can even decorate a class:
@mydecorator class Foo(object): pass
and each form is a little different to implement. This was frustrating if you wanted to create easy to use decorators where the developer didn’t need to worry about @mydecorator() working differently than @mydecorator.
The decorators.Decorator class allows you to easily create broad decorators that encompass all forms and all types (functions, methods, classes) using the same interface:
import decorators class mydecorator(decorators.Decorator): def decorate_func(self, func, *dec_args, **dec_kwargs): def decorator(*args, *kwargs): print "You passed into the decorator these arguments", dec_args, dec_kwargs print "You passed into your function these arguments", args, kwargs print "Your function is", func return func(*args, **kwargs) return decorator def decorate_class(self, klass, *dec_args, **dec_kwargs): print "You passed into the decorator these arguments", dec_args, dec_kwargs print "Your class is", klass return klass
You can then use this decorator:
@mydecorator def foo(): print "foo()" @mydecorator(1, 2, boom="blam") def bar(*args, **kwargs): print "bar()" @mydecorator class Baz(object): pass @mydecorator(1, 2, boom="blam") class Che(object): pass
Now, your decorator can decorate functions or classes, pass in arguments, or not, and you never have to worry about the subtle differences between the decorators, and best of all, you don’t have to duplicate code.
The Decorator class is good if you want to create a decorator that is totally flexible, if you want to enforce your decorator only being used for a function/method, you can use FuncDecorator. If you want to only decorate a class, use ClassDecorator, and if you want to decorate every instance of a class, use InstanceDecorator.
Whatever child class you use, you override the decorate method to return your decorator function:
import decorators class only_func(FuncDecorator): def decorate(self, func, *dec_a, **dec_kw): def decorator(*args, **kwargs): return func(*args, **kwargs) return decorator # this will work @only_func def foo(): pass # this will fail @only_func class Foo(object): pass
pip install decorators
Or, to get the latest and greatest from source:
pip install git+https://github.com/firstopinion/decorators#egg=decorators