locale.getlocale() in cmd.exe vs. Idle

Albert-Jan Roskam fomcl at yahoo.com
Tue Nov 11 15:47:01 CET 2014

----- Original Message -----
> From: Terry Reedy <tjreedy at udel.edu>
> To: python-list at python.org
> Cc: 
> Sent: Monday, November 10, 2014 9:31 PM
> Subject: Re: locale.getlocale() in cmd.exe vs. Idle
> On 11/10/2014 4:22 AM, Albert-Jan Roskam wrote:
>>  Hi,
>>  Why do I get different output for locale.getlocale() in Idle vs. cmd.exe?


> Idle runs code in an environment that is slightly altered from the 
> standard python startup environment'.  idlelib.IOBinding has this
> '''
> # Try setting the locale, so that we can find out
> # what encoding to use
> try:
>      import locale
>      locale.setlocale(locale.LC_CTYPE, "")
> '''
Hi Terry,
Thank you. Any idea why setlocale (a *setter*) returns something other than None? (this question is not related to the (None, None) thing of getlocale, just curious). Would it be a good idea to put this setlocale line in site.py? Or should it be in __init__.py to make the code more portable?

> idlelib.run, which runs in the user-code subprocess, imports IOBinding. 
> Setting LC_CTYPE is sufficient for getlocale() to not return null values.

So then I would have all the locale categories of the 'bare' locale (sorry, I don't know what else I should call it), except for LC_CTYPE, which is derived from my system. So in LC_NUMERIC I'd still have the en_US period/comma for decimal/thousand grouping, respectively, but I switch to the nl_NL LC_CTYPE. I doubt if it matters, but still: will this not introduce an ueber hard-to-find possible bug when I use re.LOCALE? 
> C:\Users\Terry>python -c "import locale; 
> print(locale.getlocale())"
> (None, None)
> C:\Users\Terry>python -c "import locale; 
> locale.setlocale(locale.LC_CTYPE, ''); print(locale.getlocale())"
> ('English_United States', '1252')
What is the difference between getlocale and getdefaultlocale anyway? The docstrings are even partially the same. The notatation of getlocale appears to be OS-specific ("English_United States" in Windows) and not Unix-like (cf. getdefaultlocale: en_US)

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