numericValue for (unicode) characters

[Dmitry Olshansky]

1/2/2013 7:24 PM, bearophile пишет:
> monarch_dodra:
>
>> The rationale for this:
>> std.ascii: I think returning -1 as a magic number should help keep the
>> code faster and with less clutter than with exceptions.
>
> For the ASCII version I have two use cases:
> - Where I want to go fast&unsafe I just use "c - '0'".
> - When I want more safety I'd like to use something as to!(), that
> raises exceptions in case of errors.
>
> A function that works on ASCII and returns -1 doesn't give me much more
> than "c - '0'". So maybe exceptions are good in the ASCII case too.
>

Then we can maybe just drop this function? What's wrong with
if(std.ascii.isNumeric(a))
    a -= '0';
else
    enforce(false);

I mean that the time to look it up in std library is much bigger then to 
roll your own with any of the 2 semantics.

Unlike the unicode version, of course. Then IMO having the std.ascii one 
is mostly just for symmetry and thus I think that both should just use 
some sentinel value.

> There is also std.typecons.nullable, it's a possibility for
> std.uni.numericValue. Generally Phobos should eat more of its dog food :-)
>

double.nan sounds more like it.

> Bye,
> bearophile


-- 
Dmitry Olshansky