LX wrote:
> Hi all, I have a question about decorators. I would like to use them
> for argument checking, and pre/post conditions. However, I don't want
> the additional overhead when I run in non-debug mode. I could do
> something like this, using a simple trace example.
>
>
> @decorator
> def pass_decorator(f, *args, **kw): # what about the slow-down that
> incurs when using pass_decorator?
> return f(*args, **kw)
>
> @decorator
> def trace_decorator(f, *args, **kw):
> print "calling %s with args %s, %s" % (f.func_name, args, kw)
> return f(*args, **kw)
>
> trace_enable_flag = False #__debug__
> trace = trace_decorator if trace_enable_flag else pass_decorator
>
>
> Trouble is, there is still an additional encapsulating function call.
> Is there any way to eliminate the extra function call altogether?
> Thanks in advance!
I think you have misunderstood certain details about decorators.
This code with a decorator:
@decorator
def hello():
print "hello world"
basically does this:
def hello():
print "hello world"
hello = decorator(hello)
so your non-decorator just needs to return the function it was passed:
def pass_decorator(func):
return func
and your trace decorator would be something like this:
def trace_decorator(func):
def show(*args, **kwargs):
print "calling %s with args %s, %s" % (func.func_name,
args, kwargs)
result = func(*args, **kwargs)
print "returning %s from %s" % (result, func.func_name)
return result
return show