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Groups > comp.lang.python > #60214
| References | <528f3f4e$0$29992$c3e8da3$5496439d@news.astraweb.com> |
|---|---|
| Date | 2013-11-22 22:44 +1100 |
| Subject | Re: Method chaining |
| From | Chris Angelico <rosuav@gmail.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3033.1385120652.18130.python-list@python.org> (permalink) |
On Fri, Nov 22, 2013 at 10:26 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> if callable(obj):
> def selfie(*args, **kw):
> # Call the method just for side-effects, return self.
> _ = obj(*args, **kw)
> return self
> return selfie
> else:
> return obj
Nice piece of magic. One limitation not mentioned is that this
completely destroys the chance to have a method return anything _other
than_ self. Since this is intended for Python's convention of
"mutators return None", I'd be inclined to check for a None return,
though that might still have some false positives.
def selfie(*args, **kw):
# Call the method for side-effects, return self if it
returns None.
_ = obj(*args, **kw)
if _ is None: return self
return _
return selfie
Either that, or manually identify a set of methods to wrap, which
could possibly be done fairly cleanly with a list of names passed to
__init__. That'd be more work, though.
ChrisA
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Method chaining Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-22 11:26 +0000
Re: Method chaining Chris Angelico <rosuav@gmail.com> - 2013-11-22 22:44 +1100
Re: Method chaining Peter Otten <__peter__@web.de> - 2013-11-22 13:08 +0100
Re: Method chaining Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-22 14:26 +0000
Re: Method chaining Peter Otten <__peter__@web.de> - 2013-11-22 16:20 +0100
Re: Method chaining Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-22 16:26 +0000
Re: Method chaining Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2013-11-22 16:52 +0000
Re: Method chaining Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2013-11-22 17:55 +0000
Re: Method chaining Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-11-22 16:38 +0100
Re: Method chaining Laszlo Nagy <gandalf@shopzeus.com> - 2013-11-23 17:08 +0100
Re: Method chaining Terry Reedy <tjreedy@udel.edu> - 2013-11-22 07:34 -0500
Re: Method chaining Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-22 14:30 +0000
Re: Method chaining Rotwang <sg552@hotmail.co.uk> - 2013-11-23 19:53 +0000
Re: Method chaining Rotwang <sg552@hotmail.co.uk> - 2013-11-24 00:28 +0000
Re: Method chaining Rotwang <sg552@hotmail.co.uk> - 2013-11-24 00:43 +0000
Re: Method chaining Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-24 14:27 +0000
Re: Method chaining Rotwang <sg552@hotmail.co.uk> - 2013-11-24 15:01 +0000
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