Comments on: Python decorator mini-study (part 2 of 3) http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/ Cool ideas revolving around computers and programming Tue, 15 Dec 2009 18:31:07 +0000 http://wordpress.com/ hourly 1 By: arjuna http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5154 arjuna Thu, 17 Jul 2008 07:17:40 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5154 Me too Thanks... I have been wondering what all this unpythonic function nesting was all about...this article made it clearer, thanks Me too Thanks… I have been wondering what all this unpythonic function nesting was all about…this article made it clearer, thanks

]]> By: hasen http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5153 hasen Tue, 08 Jul 2008 04:00:41 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5153 thanks a ton man, great article, helped me a lot!! thanks a ton man, great article, helped me a lot!!

]]> By: James Z http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5144 James Z Mon, 23 Jun 2008 07:27:10 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5144 Thanks dude, great article on python decorators. There seems to be no mention of python decorators in Dive Into Python book, nor the python tutorial on python.org. Thanks dude, great article on python decorators. There seems to be no mention of python decorators in Dive Into Python book, nor the python tutorial on python.org.

]]> By: Miscellanea and a Pycon closeout — jessenoller.com http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5064 Miscellanea and a Pycon closeout — jessenoller.com Fri, 28 Mar 2008 01:12:34 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5064 [...] Non-Typing news, this post (and this one) on Python Decorators is quite good, although more recently I saw some code that looked like [...] [...] Non-Typing news, this post (and this one) on Python Decorators is quite good, although more recently I saw some code that looked like [...]

]]> By: see whatever… » Deprecation decorator http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-3311 see whatever… » Deprecation decorator Sun, 14 Oct 2007 10:55:23 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-3311 [...] an individual message which contains information about how to avoid the deprecated method. I found this parameterized decorator example and customized it for my [...] [...] an individual message which contains information about how to avoid the deprecated method. I found this parameterized decorator example and customized it for my [...]

]]> By: muharem http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-6 muharem Fri, 20 Oct 2006 13:45:13 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-6 Hello Brian, thank you for pointing this out! I'll amend part2 to include your correction. <blockquote> #!/usr/bin/env python """variant simple decorator example""" from sys import stdout <b>def</b> interceptor(before, after): <b>def</b> interceptor_inner(f): <b>def</b> wrapper(*args, **kwargs): stdout.write(before) f(*args, **kwargs) stdout.write(after) <b>return</b> wrapper <b>return</b> interceptor_inner @interceptor('>> ', ' <<\n') <b>def</b> plf(): stdout.write("Help! I am only a poor little function!\n") <b>if</b> __name__ == '__main__': plf() e> </code> </blockquote> Hello Brian,

thank you for pointing this out! I’ll amend part2 to include your correction.

#!/usr/bin/env python
"""variant simple decorator example"""

from sys import stdout

def interceptor(before, after):
def interceptor_inner(f):
def wrapper(*args, **kwargs):
stdout.write(before)
f(*args, **kwargs)
stdout.write(after)
return wrapper
return interceptor_inner

@interceptor(‘>> ‘, ‘ <<\n’)
def plf(): stdout.write("Help! I am only a poor little function!\n")

if __name__ == ‘__main__’:
plf()

e>

]]> By: Brian http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5 Brian Fri, 20 Oct 2006 12:48:55 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-5 My indentation got mangled there. The corresponding decorator is: print """ def interceptor(before, after): | def decorator(f): | | def wrapper(*args, **kwargs): | | | stdout.write(before) | | | f(*args, **kwargs) | | | stdout.write(after) | | return wrapper | return decorator """.replace("| "," ") My indentation got mangled there. The corresponding decorator is:

print “”"
def interceptor(before, after):
| def decorator(f):
| | def wrapper(*args, **kwargs):
| | | stdout.write(before)
| | | f(*args, **kwargs)
| | | stdout.write(after)
| | return wrapper
| return decorator
“”".replace(“| “,” “)

]]> By: Brian http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-4 Brian Fri, 20 Oct 2006 12:39:14 +0000 http://muharem.wordpress.com/2006/10/19/python-decorator-mini-study-part-2-of-3/#comment-4 >Complex decorators have to be implemented as classes. This is not true - you can implement your interceptor decorator using just functions as below: def interceptor(before, after): def decorator(f): def wrapper(*args, **kwargs): stdout.write(before) f(*args, **kwargs) stdout.write(after) return wrapper return decorator What is actually happening is that _calling_ the interceptor function is returning the decorator to use, which is then called as per the normal decorator application. The same thing as is happening with the class version, where calling creates and returns an instance, which is then used as the decorator, and called. >Complex decorators have to be implemented as classes.

This is not true – you can implement your interceptor decorator using just functions as below:

def interceptor(before, after):
def decorator(f):
def wrapper(*args, **kwargs):
stdout.write(before)
f(*args, **kwargs)
stdout.write(after)
return wrapper
return decorator

What is actually happening is that _calling_ the interceptor function is returning the decorator to use, which is then called as per the normal decorator application. The same thing as is happening with the class version, where calling creates and returns an instance, which is then used as the decorator, and called.

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