Rough draft: Proposed format specifier for a thousands separator

[MRAB]

Rhodri James wrote:
[snip]
> Frankly, I'd much rather fix the locale system and extend
> the format syntax to override the default locale.  Perhaps
> something like
> 
>   financial = Locale(group_sep=",", grouping=[3])
>   print("my number is {0:10n:financial}".format(1234567))
> 
> It's hard to think of a way of extending "%" format strings
> to cope with this that won't look utterly horrid, though!
> 
The problem with your example is that it magically looks for the locale
name "financial" in the current namespace. Perhaps the name should be
registered somewhere like this:

     locale.predefined["financial"] = Locale(group_sep=",", grouping=[3])
     print("my number is {0:10n:financial}".format(1234567))