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Date: Sat, 14 Nov 2015 06:46:16 -0800 (PST)
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Subject: Re: Where is decorator in this example code?
From: fl <rxjwg98@gmail.com>
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On Saturday, November 14, 2015 at 7:38:09 AM UTC-5, Chris Warrick wrote:
> On 14 November 2015 at 13:13, fl <rx**g98@gmail.com> wrote:
> > On Saturday, November 14, 2015 at 7:11:11 AM UTC-5, fl wrote:
> >> Hi,
> >>
> >> I am learning decorator following this link:
> >>
> >> http://thecodeship.com/patterns/guide-to-python-function-decorators/
> >>
> >> When I read decorator on class, I don't see decorator taking in effect.
> >> In the following code snippet, there is the same print out if I comment out
> >> two lines 'def p_decorate(func):' and '@p_decorate'.
> >>
> >> Can you tell me what role of decorator in this code?
> [snip code]
> >
> > My OP may not be clear enough. Here is the key question. After the function
> > definition, there is no obvious decorator application in the function call:
> >
> > my_person = Person()
> > print my_person.get_fullname()
> >
> > Where is the difference between the non-decorator and decorator in this
> > example?
> >
> > Thanks,
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Have you tried executing the code with and without the decorator?
> 
> $ python2 without-decorator.py
> John Doe
> $ python2 with-decorator.py
> <p>John Doe</p>
> 
> Basically, the decorator wraps the output of your get_fullname
> function with HTML <p> tags.
> 
> (Running code examples is a great way to understand them.)
> 
> -- 
> Chris Warrick <https://chriswarrick.com/>
> PGP: 5EAAEA16

Thanks. I did run the code, but I did not check the difference carefully
between them.

A following problem now is about the args in class decorate. I do not see
args and kwargs are transferred by get_fullname(self).


If I change 

return "<p>{0}</p>".format(func(*args, **kwargs))

to

return "<p>{0}</p>".format(func(*args))

The outputs are the same.

But it is quite different if it is changed to:

return "<p>{0}</p>".format(func)

What roles are args and kwargs? I know C language.
For Python here, I don't see some rules on the args. 

Thanks again.


/////////////
def p_decorate(func):
   def func_wrapper(*args, **kwargs):
       return "<p>{0}</p>".format(func(*args, **kwargs))
   return func_wrapper

class Person(object):
    def __init__(self):
        self.name = "John"
        self.family = "Doe"

    @p_decorate
    def get_fullname(self):
        return self.name+" "+self.family

my_person = Person()

print my_person.get_fullname()