On Wed, Apr 30, 2025 at 09:33:36AM +0100, Jonathan Wakely via Std-Proposals wrote:
> On Wed, 30 Apr 2025, 05:16 Jan Schultke via Std-Proposals, <
> std-proposals_at_[hidden]> wrote:
>
> > > Which begs the question: if you need this type of configurability, why
> > don't
> > > you just use libdouble-conversion?
> >
> > It would be pretty ridiculous if you pulled in a third-party
> > dependency just because you have a comma as a radix point instead of
> > a dot.
> >
> > Also, keep in mind that this is about extending the standard library.
> > The standard library should provide the low-level, hard-to-implement
> > parts so that libraries such as double-conversion can be built on top
> > of it.
> >
> > The class you've referenced provides a large amount of fluff that the
> > user can easily do themselves. It's trivial to detect if the string is
> > "NaN" or "inf" and treat that as a NaN or infinity float. It's trivial
> > to add flags in our parser for case sensitivity, it's trivial to
> > remove a leading "0x", etc. There are a million flags and options you
> > could add here.
> >
> > What's not trivial is turning digit sequences into a floating-point
> > number. That is the low-level part of the problem that needs to be
> > supported by the standard library.
> >
>
>
> If you have already found the boundaries of the integer part and fractional
> part, represented as sequence of digits, isn't converting those digits to
> integers also easy for the user to do efficiently? Does that part belong in
> the lowest level interface?
>
> If your interface takes integers for all three arguments, then the user is
> doing the parsing steps that might need to handle digit separators.
>
> Taking strings also presents a problem for hex floats. What base is the
> string in?
>
> parse_float("1", "23");
>
> Is this 1.23e0 or 0x1.23p0?
>
> If the user has to convert "1" and "23" to integers then they can do so for
> the right base.

I might just be stupid here but how do you plan to handle leading zeroes in
the fractional part of your all integers interface?

/MF