[Python-3000] PEP 3101 clarification requests

[Talin]

Wow, excellent feedback. I've added your email to the list of reminders 
for the next round of edits.

Jim Jewett wrote:
> The PEP says:
> 
>   The general form of a standard format specifier is:
> 
>         [[fill]align][sign][width][.precision][type]
> 
> but then says:
> 
>     A zero fill character without an alignment flag
>     implies an alignment type of '='.
> 
> In the above form, how can you get a fill character without an
> alignment character?  And why would you want to support it; It just
> makes the width look like an (old-style) octal.  (The spec already
> says that you need the alignment if you use a digit other than zero.)
> 
> --------------
> 
> The explicit conversion flag is limited to "r" and "s", but I assume
> that can be overridden in a Formatter subclass.  That possibility
> might be worth mentioning explicitly.
> 
> --------------
> 
> 
>     'check_unused_args' is used to implement checking
>     for unused arguments ... The intersection of these two
>     sets will be the set of unused args.
> 
> Huh?  I *think* the actual intent is (args union kwargs)-used.  I
> can't find an intersection in there.
> 
> -----------------
>     This can easily be done by overriding get_named() as follows:
> 
> I assume that should be get_value.
> 
>     class NamespaceFormatter(Formatter):
>           def __init__(self, namespace={}, flags=0):
>               Formatter.__init__(self, flags)
> 
> but the Formatter class took no init parameters -- should flags be
> added to the Formatter constructor, or taken out of here?
> 
> The get_value override can be expressed more simply as
> 
>     def get_value(self, key, args, kwds):
>         try:
>             # simplify even more by assuming PEP 3135?
>             super(NamespaceFormatter, self).get_value(key, args, kwds)
>         except KeyError:
>             return self.namespace[name]
> 
> The example usage then takes globals()...
> 
>         fmt = NamespaceFormatter(globals())
>         greeting = "hello"
>         print(fmt("{greeting}, world!"))
> 
> Is there now a promise that the objects returned by locals() and
> globals() will be "live", so that they would reflect the new value of
> "greeting", even though it was set after the Formatter was created?
> 
> -jJ
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