Proposal: shorthand syntax for initializing arbitrary-precision ("bigint") numbers?

php.internals

tyson andre

6 years ago
Hi internals, https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt was a similar approach another dynamically typed language recently took to support convenient arbitrary precision. What are your thoughts on making `123_456_000_000_000_000_000_000n` a shorthand for `gmp_init('123456000000000000000000')` (or a call with equivalent results) (similar to existing backtick string syntax is a shorthand for `shell_exec()`) GMP objects already overrides numeric operators. (but having number-like syntax would make code using those more readable) Supporting bigints as anything other than explicitly different objects in PHP's type system seemed from a discussion thread 5 years ago to have several drawbacks - https://externals.io/message/77863 : - Native bigints by default as a result of integer operations would cause a B.C. break for extensions for php user code relying on float behavior. The way that division would be handled would change, for example. - Decrease in performance was seen during a patch being worked on 5 years ago to automatically convert overflowing integer operations to big integers - Requirement to update opcache's inferences to support big integers A prototype implementation is available at https://github.com/php/php-src/pull/5930 which goes into more details about implementation concerns, licensing of GMP, and other drawbacks of representing them as a GMP/BigInt class instance instead of something separate from regular objects. - Tyson

Andrew Faulds

6 years ago
Hi Tyson, tyson andre wrote:
> What are your thoughts on making `123_456_000_000_000_000_000_000n` a shorthand for `gmp_init('123456000000000000000000')` (or a call with equivalent results) > (similar to existing backtick string syntax is a shorthand for `shell_exec()`)
We could do that, but maybe this is a good opportunity to do something with a wider benefit than GMP by having a generalised solution? GMP is already special in some ways and it would be a shame to have even more functionality that privileges it. For example, what if we allowed string prefixes to have special user-defined meanings, like: n"123_456" // expands to: gmp_init('123_456') u"foo bar" // expands to: new UnicodeString("foo bar") (some class I made up) d"123.456" // expands to: new Decimal("123.456") (also an imaginary class) This would be a similar idea to JavaScript's template string tags: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals How you'd define the mappings from prefixes to executed code, I'm not sure, but we could just make it call a function by that name in the current namespace… though that would prompt the question “why not just write `d("123.456")`, which is already possible?” and I don't have a good answer to that :) Regards, Andrea