Re: [dev] Re: json

From: Mattias Andrée <maandree_AT_kth.se>
Date: Sat, 15 Jun 2019 22:39:44 +0200

On Sat, 15 Jun 2019 22:11:13 +0200
Wolf <wolf_AT_wolfsden.cz> wrote:

> Hello,
>
> On , Mattias Andrée wrote:
> > Wouldn't it just complicate matters if you needed to specify whether a
> > number is an integer or a real value;
>
> Could you not just consider sequence of [0-9]+ to be an integer and
> anything with other characters either invalid or float? Not sure, I'm in
> no means a parser expert, so I might be missing something fundamental
> here.

A bit: floats can be significantly larger than ints, (and negative
numbers) of course. However the syntax could be simple: \+?[0-9]+
could be unsigned int, -[0-9]+ could be signed int, and
[+-]?[0-9]*.[0-9]+ and [+-]?[0-9]+.[0-9]* could be float. But still,
only using `long double` or arbitrary precision floating-point
numbers is simpler in my mind, in usage, in specification, and in
implementation.

I would also prefer if hexadecimal encoding of floats where
supported (to eliminate loss of precision).

>
> > Additionally, I think you would want to support for arbitrary
> > precision. Again, the software can just check if arbitrary precision
> > is required, no need to complicate the syntax.
>
> Agreed, arbitrary precision would be nice, and currently is probably
> done via strings if it's needed. But not sure if it's something you want
> to have in the standard though as a separate type. Passing them via
> string is probably good enough for specialized applications that do need
> them.
>
> > What should a library do with parsed numbers that are too large or too
> > precise?
>
> Report an error and provide flag to do best-possible parsing if user
> wants the number anyway knowing it will not be precise. Not do a silent
> guesstimate.
>
>
>
> Basically, I think the fact that following returns false is stupid:
>
> + $ ruby -rjson -e 'puts({ num: (?9 * 100).to_i }.to_json)' \
> | node -p 'var fs = require("fs");
> JSON.stringify(JSON.parse(fs.readFileSync(0, "utf-8")));' \
> | ruby -rjson -e 'puts (?9 * 100).to_i == JSON.parse(STDIN.read)["num"]'
> false
>
> That means that despite all libraries in the chain fully implementing
> the JSON standard, not silently corrupting the data during the
> round-trip is not guaranteed.
>
> W.
Received on Sat Jun 15 2019 - 22:39:44 CEST