Re: io.format (was: Reported to the Bloat Police: string.pack, .unpack and .packsize!)

[Daurnimator <quae@...>]

On 23 August 2015 at 12:02, Rena <hyperhacker@gmail.com> wrote:
> On Sat, Aug 22, 2015 at 5:08 PM, Sean Conner <sean@conman.org> wrote:
>> [2]     Python has an alternative format specification where you can specify
>>         which parameter (either by name or position in the argument list) to
>>         use.  This makes it a bit easier to translate messages.
>>
>
> This is actually supported by POSIX string formatting[1]:
>
> printf("The %1$s has %2$d feet.\n", "cat", 4);
> printf("There are %2$d feet on a %1$s.\n", "cat", 4);
>
> Unfortunately Lua's string.format doesn't support it.[2]
>
> [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html
> - "Conversions can be applied to the nth argument after the format in
> the argument list, rather than to the next unused argument. In this
> case, the conversion specifier character % (see below) is replaced by
> the sequence "%n$", where n is a decimal integer in the range
> [1,{NL_ARGMAX}], giving the position of the argument in the argument
> list."
>
> [2] On the other hand, Lua supports named arguments:
>> words={subject='cat', feet=4}
>> 'The {subject} has {feet} feet'):gsub('%b{}', function(s) return words[s:sub(2,-2)] end)
> The cat has 4 feet    2
> (The extra "2" is the second return value from gsub. Also, this method
> won't work with numeric keys - it'll look for the key "1" rather than
> 1 - but this is easily fixed.)
>

Interestingly enough; lua 4.0 had this.
http://www.lua.org/manual/4.0/manual.html#format