On 9/28/2010 6:02 PM, Nick Donohue wrote:
I came across this code just now:
def time_me(function):
def wrap(*arg):
start = time.time()
r = function(*arg)
end = time.time()
print "%s (%0.3f ms)" %(function.func_name, (end-start)*1000)
return wrap
@time_me
def some_function(somearg)
As others noted, this is an bad example of a decorator. Please forget
it. Let us move on...
#deco
def func_name(*args): pass
is syntactic sugar for (which is to say, is almost and for practical
purposes is exactly equivalent to)
def func_name(*args): pass
func_name = deco(func_name)
Indeed, Python did well without them until they were added. But there
are 2 advantages of the decorator syntax:
1. Without it, one write (and read!) func_name 3 times instead of 1. One
of the use cases that motivated decorators was a situation where someone
was required to wrap numerous functions with stylized names about 30
chars long, like 'get_hopscotch_version_a_code_123x76'
2. Understanding the code may require that one know that it will never
see the light of day as is. If the body is several lines, the wrapping
call may be hard to see. To put it another way, the wrapping calls often
belong near the doc string since they are part of a high-level overview
of the function.
--
Terry Jan Reedy
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