[Python-3000] More PEP 3101 changes incoming

[Greg Ewing]

Ron Adam wrote:
> The way to think of 'repr' and 'str' is that of a general "object" format 
> type/specifier.  That puts str and repr into the same context as the rest 
> of the format types.  This is really a point of view issue and not so much 
> of a semantic one.  I think {0:r} and {0:s} are to "object", as {0:d} and 
> {0:e} are to "float" ...  just another relationship relative to the value 
> being formatted.  So I don't understand the need to treat them differently.

There's no need to treat 's' specially, but 'r' is different,
at least if we want

    "{0:r}".format(x)

to always mean the same thing as

    "{0:s}".format(repr(x))

To achieve that without requiring every __format__ method
to recognise 'r' and handle it itself is going to require
format() to intercept 'r' before calling the __format__
method, as far as I can see. It can't be done by str,
since by the time str.__format__ gets called, the object
has already been passed through str(), and it's too late
to call repr() on it.

-- 
Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | Carpe post meridiem!          	  |
Christchurch, New Zealand	   | (I'm not a morning person.)          |
greg.ewing at canterbury.ac.nz	   +--------------------------------------+