Of course that would still leave the door open for struct.pack support (maybe recognized by having the string start with <,=, > or @). Pro: everybody who currently uses struct.pack will love it. Con: the struct.pack mini-language is pretty inscrutable if you don't already know it. (And no, I don't propose to invent a different mini-language -- it's just easier to figure out where to find docs for this when the code explicitly imports the struct module.) On Wed, Oct 7, 2015 at 10:53 AM, Eric V. Smith <eric@trueblade.com> wrote:
On 10/07/2015 12:25 PM, Guido van Rossum wrote:
I think bf'...' should be compared to b'...' % rather than to f'...'. IOW bf'...' is to f'...' as b'...'% is to '...'%.
I'm leaning this way, at least in the sense of "there's a fixed number of known types supported, and there's no extensible protocol involved.
Eric.
On Wed, Oct 7, 2015 at 5:34 AM, Andrew Barnert <abarnert@yahoo.com <mailto:abarnert@yahoo.com>> wrote:
On Oct 7, 2015, at 04:35, Nick Coghlan <ncoghlan@gmail.com <mailto:ncoghlan@gmail.com>> wrote: > >> On 4 October 2015 at 08:25, Andrew Barnert <abarnert@yahoo.com
<mailto:abarnert@yahoo.com>> wrote:
>> Nick's suggestion of having it do %-formatting makes sense. Yes,
it means
>> that {count:03} is an error and you need '{count:03d}', which is >> inconsistent with f-strings. But that seems like a much less
serious problem
>> than bytes formatting not being able to handle bytes. > > Exactly, if someone is mistakenly thinking > bf"{header}{content}{footer}" is equivalent to > f"{header}{content}{footer}".encode(), they're likely to get
immediate
> noisy errors when they start trying to format fields.
Except that multiple people in this thread are saying that'd exactly what it should mean (which I think is a very bad idea).
> The parallel I'd attempt to draw is that: > > f"{header}{content}{footer}" is to "{}{}{}".format(header,
content, footer)
> > as: > > bf"{header:b}{content:b}{footer:b}" would be to b"%b%b%b" % > (header, content, footer) > > To make the behaviour clearer in the latter case, it may be
reasonable
> to *require* an explicit field format code, since that corresponds > more closely to the mandatory field format codes in mod-formatting.
Are you suggestive that if a format specifier is given, it must include the format code (which seems perfectly reasonable to me--guessing that :3 means %3b is likely to be wrong more often than it's right…), or that a format specifier must always be given, with no default to :b (which seems more obtrusive and solves less of a problem).
-- --Guido van Rossum (python.org/~guido <http://python.org/~guido>)
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-- --Guido van Rossum (python.org/~guido)