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To: Andrea Faulds <ajf@ajf.me>, "internals@lists.php.net"
	<internals@lists.php.net>
Thread-Topic: [PHP-DEV] Re: Proposal: shorthand syntax for initializing
 arbitrary-precision("bigint") numbers?
Thread-Index: AQHWbYG0jbTFMj2RlkKxINS6VcUHrKkuO34J
Date: Sat, 8 Aug 2020 14:19:28 +0000
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Subject: Re: [PHP-DEV] Re: Proposal: shorthand syntax for initializing
 arbitrary-precision("bigint") numbers?
From: tysonandre775@hotmail.com (tyson andre)

Hi Andrea,=0A=
=0A=
> > What are your thoughts on making `123_456_000_000_000_000_000_000n` a s=
horthand for `gmp_init('123456000000000000000000')` (or a call with equival=
ent results)=0A=
> > (similar to existing backtick string syntax is a shorthand for `shell_e=
xec()`)=0A=
> =0A=
> We could do that, but maybe this is a good opportunity to do something =
=0A=
> with a wider benefit than GMP by having a generalised solution? GMP is =
=0A=
> already special in some ways and it would be a shame to have even more =
=0A=
> functionality that privileges it.=0A=
> =0A=
> For example, what if we allowed string prefixes to have special =0A=
> user-defined meanings, like:=0A=
>=0A=
>   n"123_456" // expands to: gmp_init('123_456')=0A=
>   u"foo bar" // expands to: new UnicodeString("foo bar") (some class I =
=0A=
made up)=0A=
>=A0=A0 d"123.456" // expands to: new Decimal("123.456") (also an imaginary=
 =0A=
class)=0A=
> =0A=
> This would be a similar idea to JavaScript's template string tags: =0A=
> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Templat=
e_literals=0A=
> =0A=
> How you'd define the mappings from prefixes to executed code, I'm not =0A=
> sure, but we could just make it call a function by that name in the =0A=
> current namespace=85 though that would prompt the question =93why not jus=
t =0A=
> write `d("123.456")`, which is already possible?=94 and I don't have a =
=0A=
> good answer to that :)=0A=
=0A=
I'd feel like the former syntax would be more readable/familiar.=0A=
=0A=
https://en.cppreference.com/w/cpp/language/user_literal also exists. It sup=
ports literals like `2.0_km` or `"one"_w.=0A=
`void operator "" _km(long double); // OK, will be called for 1.0_km`=0A=
A brand new type of operator function separate from global functions (possi=
bly with autoloading) would be one possible way to execute that.=0A=
=0A=
That being said, I don't know extending that syntax to user-defined functio=
ns would pass as an RFC, and I don't personally interest in adding it.=0A=
=0A=
- In C++, you'd know if there was a bug at compile time.=0A=
  The C++ compiler would tell you that the program could not contain `1.0_k=
m + 1.0_Litres` or `1.0_km + 2` before the program could run.=0A=
- Maybe this could be initially limited to C extensions (PECLs) during init=
ialization?=0A=
  The ability to perform operations on user-defined classes is limited beca=
use https://wiki.php.net/rfc/userspace_operator_overloading didn't pass. =
=0A=
- User-defined operators would also enable code like `$x =3D download_url"h=
ttps://....";`, which may cause confusion reviewing code but should hopeful=
ly be rare in practice.=0A=
- If somebody ended up adding user-defined literal syntaxes, I'd really hop=
e that those would be separate from global function symbols and unambiguous=
ly resolved (e.g. by not having namespaces, or by requiring that the operat=
or be explicitly imported to be used)=0A=
- Different frameworks may end up with conflicting definitions of the same =
operator for short operators.=0A=
- Also, there'd be no indication if there were typos such as `$a =3D yeeld"=
END";` and I'm not sure how lexing would work with prefixes. Suffixes may w=
ork, I'm not sure.=0A=
=0A=
Thanks,=0A=
- Tyson=