[Python-3000] More PEP 3101 changes incoming

[Greg Ewing]

Ron Adam wrote:
> What about mismatched specifiers?

It's not clear exactly what you mean by a "mismatched"
specifier.

Some types may recognise when they're being passed
a format spec that belongs to another type, and try
to convert themselves to that type (e.g. applying
'f' to an int or 'd' to a float).

If the type doesn't recognise the format at all,
and doesn't have a fallback type to delegate to
(as will probably be the case with str) then
you will get an exception.

> I think the opinion so far is to let the objects __format__ method 
> determine this, but we need to figure this out what the built in types 
> will do.

My suggestions would be:

   int - understands all the 'integer' formats
         (d, x, o, etc.)
       - recognises the 'float' formats ('f', 'e', etc.)
         and delegates to float
       - delegates anything it doesn't recognise to str

   float - understands all the 'float' formats
         - recognises the 'integer' formats and delegates to int
         - delegates anything it doesn't recognise to str

   str - recognises the 'string' formats (only one?)
       - raises an exception for anything it doesn't understand

I've forgotten where 'r' was supposed to fit into
this scheme. Can anyone remind me?

--
Greg