[Python-Dev] Re: Alternative Implementation for PEP292:SimpleString Substitutions

[M.-A. Lemburg]

Guido van Rossum wrote:
>>Templates are meant to template *text* data, so Unicode is
>>the right choice of baseclass from a design perspective.
> 
> Only in Python 3.0.

We better start early to ever reach the point of making
a clear distinction between text and binary data in P3k.

> But even so, deriving from Unicode (or str) means the template class
> inherits a lot of unwanted operations. While I can see that
> concatenating templates probably works, slicing them or converting to
> lowercase etc. make no sense. IMO the standard Template class should
> implement a "narrow" interface, i.e. *only* the template expansion
> method (__mod__ or something else), so it's clear that other
> compatible template classes shouldn't have to implement anything
> besides that. This avoids the issues we have with the mapping
> protocol: when does an object implement enough of the mapping API to
> be usable? That's currently ill-defined; sometimes, __getitem__ is all
> you need, sometimes __contains__ is required, sometimes keys, rarely
> setdefault.

Looks like it's ont even clear what templating itself should
mean... you're talking about a templating interface here, not an
object type, like Barry is (for the sake of making Templates compatible
to i18n tools like gettext).

-- 
Marc-Andre Lemburg
eGenix.com

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