W dniu nie, 10.09.2017 o godzinie 03∶05 +1200, użytkownik Kent Fredric
napisał:
> On Fri, 8 Sep 2017 13:19:23 +0200
> Michał Górny <mgo...@gentoo.org> wrote:
>
> > a. getting wider review and some real-life testing before
> > the specification is set in stone, and
>
> Any thoughts on a function that would represent a dotted-decimal style version
> as a floating point string?
>
> eg:
>
> ver_float 0.1.0 -> 0.001
> ver_float 0.10.0 -> 0.010
> ver_float 0.100.0 -> 0.100
>
> That's of course *the most* generic example I can offer, but seeing
> this sort of transformation is commonly needed in the world of perl, I
> thought maybe now is a good time to mention something.
>
> Sadly, its just the sort of idea that if done wrong, would be no use.
>
> For instance, sometimes you want:
>
> ver_float 0.1.0 -> 0.0010
>
> Or
>
> ver_float 0.1.1 -> 0.001001
>
> The two key things here is to know:
>
> 1. How many digits each position represents
> 2. The maximum number of digits to represent
>
> So, some ideas in that regard are:
>
> ver_float ${INPUT} ${PRECISION}
>
> Where the values per position are fixed, so:
>
> ver_float 0.1 3 -> 0.001
> ver_float 0.1 2 -> INVALD # fidelity loss by truncation
> ver_float 0.10 2 -> 0.01 # permitted because there's no fidelity loss
> by truncation
> ver_float 0.100 1 -> 0.1 # permitted because there's no fidelity loss
> by truncation
> ver_float 0.100 2 -> 0.10
> ver_float 0.100 3 -> 0.100
> ver_float 0.101 1 -> INVALID # fidelity loss by truncation
>
> ver_float 0.1 5 -> 0.00100
> ver_float 0.1.1 5 -> INVALID, need 6 digits to represent 0.1.1
>
> ver_float 0.1.1 6 -> 0.001001
>
>
> Or say,
>
> ver_float ${INPUT} ${PATTERN}
>
> Where "pattern" is a string like 3-3-3 indicating how to map digits to numbers
>
> ver_float 0.1 3 -> 0.001
> ver_float 0.1 2 -> 0.01
> ver_float 0.1 1 -> 0.1
> ver_float 0.1.1 3 -> # INVALID, no map for '.1'
> ver_float 0.1.1 3-3 -> 0.001001
> ver_float 0.1.10 3-3 -> 0.001010
> ver_float 0.1.10 2-2 -> 0.0110
> ver_float 0.10.10 2-2 -> 0.1010
> ver_float 0.100.10 2-2 -> # INVALID, can't map "100" into 2 characters
>
> Though I suspect you'd want both features ...
>
> ver_float ${INPUT} ${PATTERN} ${TRUNCATION_LENGTH}
>
> Because we do need packages where
>
> 0.123.10 means 0.1231
>
> Either way, much of this is probably a time wasting bad idea.
>
> But I thought I'd just
>
> ( •_•)
>
> ( •_•)>⌐■-■
>
> (⌐■_■)
>
> Float it by you.
>
I'm not sure if there's a serious proposal behind all this but I suppose
it's all just perl-specific insanity that is of no value to everyone
else.
--
Best regards,
Michał Górny
