[Python-3000] More PEP 3101 changes incoming

[Ron Adam]

Talin wrote:
> Ron Adam wrote:
>> Now here's the problem with all of this.  As we add the widths back 
>> into the format specifications, we are basically saying the idea of a 
>> separate field width specifier is wrong.
>>
>> So maybe it's not really a separate independent thing after all, and 
>> it just a convenient grouping for readability purposes only.
> 
> I'm beginning to suspect that this is indeed the case.

Yes, I believe so even more after experimenting last night with specifier 
objects.

for now I'm using ','s for separating *all* the terms.  I don't intend that 
should be used for a final version, but for now it makes parsing the terms 
and getting the behavior right much easier.

      f,.3,>7     right justify in field width 7, with 3 decimal places.

      s,^10,w20   Center in feild 10,  expands up to width 20.

      f,.3,%

This allows me to just split on ',' and experiment with ordering and see 
how some terms might need to interact with other terms and how to do that 
without having to fight the syntax problem for now.

Later the syntax can be compressed and tested with a fairly complete 
doctest as a separate problem.


> Before we go too much further, let me give out the URLs for the .Net 
> documentation on these topics, since much of the current design we're 
> discussing has been inspired by .Net:
> 
> http://msdn2.microsoft.com/en-us/library/dwhawy9k.aspx
> http://msdn2.microsoft.com/en-us/library/0c899ak8.aspx
> http://msdn2.microsoft.com/en-us/library/0asazeez.aspx
> http://msdn2.microsoft.com/en-us/library/c3s1ez6e.aspx
> http://msdn2.microsoft.com/en-us/library/az4se3k1.aspx
> http://msdn2.microsoft.com/en-us/library/txafckwd.aspx
> 
> I'd suggest some study of these. Although I would warn against adopting 
> this wholesale, as there are a huge number of features described in 
> these documents, more than I think we need.
> 
> One other URL for people who want to play around with implementing this 
> stuff is my Python prototype of the original version of the PEP. It has 
> all the code you need to format floats with decimal precision, 
> exponents, and so on:
> 
> http://www.viridia.org/hg/python/string_format?f=5e4b833ed285;file=StringFormat.py;style=raw 

Thanks, I'll take a look at it.

Cheers,
    Ron