Decorum 0.4.5

Tool for writing simple decorators

Decorum is a simple tool which aims to make it easier to write flexible and simple decorators. It can also act similarly to functools.wraps.

Typical usage looks like this:

from decorum import decorator

@decorator
class my_decorator:
    def wraps(self, f):
        print "I'm returning the function! You can keep it!"
        return f

Decorum lets you write decorators with and without arguments in a unified way. Your decorator can be used with or without arguments, called or not, and it will work the same way:

@my_decorator
def foo(x): print x

Is identical to:

@my_decorator()
def foo(x): print x

Writing decorators

Decorum provides two easy ways to write your own decorators. You can use decorum.decorator to decorate decorator classes, or you can directly subclass decorum.Decorum. There are only two methods to be aware of when writing your own decorators. Define a wraps method to handle the actual decoration and return the decorated function, and optionally define an init method to handle any arguments you want to accept, and handle basic setup (it’s called before decoration by __init__, you can use it in a similar fashion to a real __init__ method). By default decorum will try to keep assign certain attributes to the wrapped function for you, namely __doc__ and __name__. You can set keep_attrs to None to turn this off, or provide it with a list of attributes you want applied to the returned decorated function.

Here is a slightly fancier example:

from decorum import decorator

@decorator
class fancy:
    def init(self, arg=None):
        self.arg = arg

    def wraps(self, f):
        if self.arg:
            def newf():
                print self.arg
        else:
            def newf():
                print 'wut'
        return newf

@fancy
def foo():
    pass
foo()

@fancy('woof')
def foo():
    pass
foo()

# prints
wut
woof