[Python-Dev] Behaviour change of object().format() in 3.4

[R. David Murray]

On Tue, 06 May 2014 16:45:52 +0200, James Swift <james at 3dengineer.com> wrote:
> Hi,
> 
> In 3.3 I could do the following
> 
> >>> "{x:s}".format(**{'x': [1, 2, 3]})
> '[1, 2, 3]'
> 
> But in 3.4
> 
> >>> "{x:s}".format(**{'x': [1, 2, 3]})
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: non-empty format string passed to object.__format__
> 
> 
> Is this intentional?

Yes.  There was a deprecation warning for this in 3.3, and it
is now an error in 3.4.

For more information, see http://bugs.python.org/issue7994.

--David