[Python-Dev] Decorators after 'def' should be reconsidered (original) (raw)

barnesc at engr.orst.edu barnesc at engr.orst.edu
Wed Aug 11 01:12:58 CEST 2004

In the discussion on decorators months ago, solutions involving special syntax inside the block were ruled out early on. Basically, you shouldn't have to peek inside the block to find out important external properties of the function.

--Guido van Rossum (home page: http://www.python.org/~guido/)

I disagree.

The most important part of a function is the first def line.

If you place other stuff before the def line, you make it harder to grep for the def line.

Compare:

Option A

""" Hi,

Performs a binary operation.

Docstring. """ @staticmethod @synchronized(lockvar) def f(a, b): return a + b

""" Now,

Performs a simple operation. """ @classmethod def g(a): return a

Option B

def f(a, b): @staticmethod @synchronized(lockvar) """ Hi,

Performs a binary operation.

Docstring.
"""
return a + b

def g(a): @classmethod """ Now,

Performs a simple operation.
"""
return a

Now, forget everything you've learned about Python. Forget that @ symbols are ugly.

Note that Option A causes you to skim all the way through the docstring and the decorators to find out which function is being defined. At this point, you have to start over at the docstring, to find out what the function actually does.

Option A is especially painful when a large number of functions are thrown into a module. It is almost impossible to grep efficiently for the function names. Thus the code appears disorganized, and messy.

It seems strange that Option B was "ruled out early on." Option B is clearly more readable.

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