[Python-Dev] Re: Alternative ImplementationforPEP292:SimpleString Substitutions

[Brett C.]

Martin v. Löwis wrote:
> Raymond Hettinger wrote:
> 
>> [Brett]
>>
>>> I suspect stating exactly what a valid Python
>>> identifier contains as you did in parentheses above will be enough.
>>
>>
>>
>> Given the template, u'¿Puede volver $hoy o $mañana?', you think $ma is
>> an intended placeholder name and that ñ should be a delimiter just like
>> whitespace and punctuation?
> 
> 
> No, I think Brett (and apparently nearly everybody else) thinks that
> such a template will not be written over the course of the next five
> years, except for demonstration purposes. Instead, what will be written
> is u'¿Puede volver $today o $tomorrow?' because the template will be
> a translation of the original English template, and, during translation,
> placeholder names must not be changed (although I have difficulties
> imagining possible values for today or tomorrow so that this becomes
> meaningful).
> 

Actually, that wasn't what I was thinking, but that also works.  My 
original thinking is that Template will throw a fit and that's fine 
since they didn't follow the rules.

>> If end users always follow the rules, this will never come up.  If they
>> don't, should there be error message or a silent failure?
> 
> 
> There is always a chance of a silent failure in SafeTemplates, even with
> this rule added - this is the purpose of SafeTemplates. With a Template,
> you will get a KeyError. In any case, the failure will not be completely
> silent, as the user will see $mañana show up in the output.
> 

Right, my other reason for not thinking this is a big issue.  If you use 
SafeTemplate you will have to watch out for silent problems like this 
anyway.

I just don't think it will be a big problem.  And if people want the 
support they will just use a pure Unicode Template subclass (perhaps we 
should include that in the module?).

-Brett