Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #10482 > unrolled thread

Re: NoneType and new instances

Back to article view | Back to comp.lang.python

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: NoneType and new instances Chris Angelico <rosuav@gmail.com> - 2011-07-29 07:16 +1000
    Re: NoneType and new instances Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-07-29 11:29 +1000

#10482 — Re: NoneType and new instances

On Fri, Jul 29, 2011 at 7:03 AM, Ethan Furman <ethan@stoneleaf.us> wrote:
> I'll use a lambda to get around it, but that's not very elegant.  Why
> shouldn't NoneType be able to return the singleton None?

Why a lambda?

def ThisFunctionWillReturnNone():
    pass

Although, since the returning of None is crucial to it, it'd probably
be better to explicitly "return None". But minimalist useful functions
are amusing.

ChrisA

[toc] | [next] | [standalone]

#10495

Chris Angelico wrote:

> On Fri, Jul 29, 2011 at 7:03 AM, Ethan Furman <ethan@stoneleaf.us> wrote:
>> I'll use a lambda to get around it, but that's not very elegant.  Why
>> shouldn't NoneType be able to return the singleton None?
> 
> Why a lambda?
> 
> def ThisFunctionWillReturnNone():
>     pass

This is a good use-case for a lambda. Ethan's use-case is a dict of
constructors:

     fielddef = { 'empty':some_func, 'null':some_func }

There's no need to expose the constructor outside of the dict, hence:

     fielddef = { 'empty': str, 'null': lambda: None }

does the job. No need for a top-level named function.


-- 
Steven

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web