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dummy, underscore and unused local variables

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  dummy, underscore and unused local variables Tim Johnson <tim@johnsons-web.com> - 2011-06-13 07:37 -0800
    Re: dummy, underscore and unused local variables Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-13 16:02 +0000
      Re: dummy, underscore and unused local variables Chris Angelico <rosuav@gmail.com> - 2011-06-14 02:28 +1000
    Re: dummy, underscore and unused local variables Ben Finney <ben+python@benfinney.id.au> - 2011-06-14 10:39 +1000

#7523 — dummy, underscore and unused local variables

Consider the following code:
for i in range(mylimit):
    foo()
running pychecker gives me a 
"""
Local variable (i) not used 
"""
complaint.
If I use 
for dummy in range(mylimit):
    ....
## or
for _ in range(mylimit):
    ....
I get no complaint from pychecker.	
I would welcome comments on best practices for this issue.
NOTE: I see much on google regarding unused local variables, 
however, doing a search for 'python _' hasn't proved fruitful.

I would like to see comments here specifically on the use for `range'

On a related note: from the python interpreter if I do
>>> help(_) 
I get 
Help on bool object:

class bool(int)
 |  bool(x) -> bool
 ......
 I'd welcome comments on this as well.

 :) I expect to be edified is so many ways, some
 of them unexpected.

 thanks
-- 
Tim 
tim at johnsons-web dot com or akwebsoft dot com
http://www.akwebsoft.com

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#7528

On Mon, 13 Jun 2011 07:37:02 -0800, Tim Johnson wrote:

> Consider the following code:
[...]

You know Tim, if you hadn't blocked my email address in a fit of pique 
over something that didn't even involve you, you would have seen my 
answer to your question on the tutor@python.org mailing list yesterday.

http://code.activestate.com/lists/python-tutor/83236/

Yes, I realise that Tim probably won't see this either. I'm just making a 
point.



-- 
Steven

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#7533

On Tue, Jun 14, 2011 at 2:02 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Mon, 13 Jun 2011 07:37:02 -0800, Tim Johnson wrote:
>
>> Consider the following code:
> [...]
>
> You know Tim, if you hadn't blocked my email address in a fit of pique
> over something that didn't even involve you, you would have seen my
> answer to your question on the tutor@python.org mailing list yesterday.
>
> http://code.activestate.com/lists/python-tutor/83236/
>
> Yes, I realise that Tim probably won't see this either. I'm just making a
> point.
>
>
>
> --
> Steven
> --
> http://mail.python.org/mailman/listinfo/python-list
>

As he says, edification comes from a variety of odd sources... I
didn't know the linting ignored a variable called 'dummy' or '_'.
Worth knowing!

ChrisA

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#7576

Tim Johnson <tim@johnsons-web.com> writes:

> If I use 
> for dummy in range(mylimit):
>     ....
> ## or
> for _ in range(mylimit):
>     ....
> I get no complaint from pychecker.	
> I would welcome comments on best practices for this issue.

I have argued in the past against overloading the name ‘_’ for this
<URL:http://mail.python.org/pipermail/python-list/2008-January/523777.html>
since it has other, unrelated, meanings already established.

Other responses in that thread are also useful.

-- 
 \      “I find the whole business of religion profoundly interesting. |
  `\     But it does mystify me that otherwise intelligent people take |
_o__)                                    it seriously.” —Douglas Adams |
Ben Finney

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