Are decorators really that different from metaclasses...

Paul Morrow pm_mon at yahoo.com
Tue Aug 24 18:29:38 CEST 2004


...that they warrant an entirely new syntax?  It seems that they are 
very similar in a very significant way --- they alter the default 
behavior of something.  IMO, it's not a stretch to say that they 
'parallel' metaclasses; that they are to functions/methods what 
metaclasses are to classes.  So why don't they share a similar syntax?

    class Foo:
       """ This is the docstring for class Foo. """
       __metaclass__ = M
       # body of class goes here


    def baz():
       """ This is the docstring for function baz. """
       __features__ = synchronized, memoized
       # body of function goes here.


I personally find the above baz function aesthetically appealing.  Does 
anyone else feel this way?  For contrast, below is the same function 
written in the proposed A1 and J2 [*] syntaxes (respectively).


    @synchronized
    @memoized
    @doc(""" This is the docstring for function baz. """)
    def baz():
       # body of function goes here.


    decorate:
       """ This is the docstring for function baz. """
       synchronized
       memoized
    def baz():
       # body of function goes here.


* if J2 is accepted, the name 'decorate' may be replaced with some other 
keyword, but I believe that the structure of the syntax would stay the same.

Paul




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