[Python-Dev] str.format_from_mapping (original) (raw)

Eric Smith eric at trueblade.com
Sun Oct 31 23:32:12 CET 2010

On 10/31/2010 6:28 PM, Glenn Linderman wrote:

On 10/31/2010 2:02 PM, Benjamin Peterson wrote:

2010/10/31 Antoine Pitrou<solipsis at pitrou.net>:

> On Sun, 31 Oct 2010 16:39:44 -0400 > Eric Smith<eric at trueblade.com> wrote: >

>> What are your thoughts on adding a str.formatfrommapping (or similar >> name, maybe the suggested "formatmap") to 3.2? See >> http://bugs.python.org/issue6081 . This method would be similar to >> "%(foo)s %(bar)s" % d, where d is a dict (or rather any mapping object), >> but of course would use str.format syntax: "{foo} >> {bar}".formatfrommapping(d). > > I must be missing something, but what's the difference with > XXX.format(**d)? It allows arbitrary mappings. Other than the language moratorium, why are arbitrary mappings not allowed for the (**d) syntax?

An arbitrary mapping would be converted to a dict. That disallows using a subclass with missing defined, among other things. See the discussion in the issue.

More information about the Python-Dev mailing list