On Wed, Dec 6, 2023 at 10:36 PM Alex Pravdin <alex.prav...@interi.co> wrote:
> Hello internals, > > > This is the second round of the discussion regarding arbitrary precision > scalar type integration into PHP. The previous part: > https://marc.info/?l=php-internals&m=168250492216838&w=2 was initiated by > me before deep diving into the work with decimals in PHP. After 6 months > of > working, I would like to update my proposal taking into account my > experience and the previous discussion. > All builtin functions that currently accept float also accept decimal. So > users don't need to care about separate function sets, and PHP developers > don't need to maintain separate sets of functions. If such functions get > the decimal parameter, they return decimal. If they have more than one > float parameter and mixed float and decimal passed, decimals converted to > float by default. If "default_decimal" or "as_decimal" used, float is > converted to decimal with the warning. > > You are going to run into some very difficult corners on this one. For the last... 8 years i guess? I have been working on an arbitrary precision library for PHP in userland. It utilizes BCMath, ext-decimal, and GMP, depending on what is installed and what kind of operation you are performing. So, the functions that currently accept floats include functions such as `sin()` or `atan()`. These functions are not at all trivial to do to arbitrary precision. In fact, the VAST majority of the work I have done on my library has been to handle cases like "What do I do if the user wants 2.921 ** 4.293810472934854?" or "How will I guarantee the precision that the user requested for `tan()` in an efficient way?" Now, libmpdec is going to actually have implementations for most of this stuff that you can call directly, but if the PHP function `sin()` isn't capable of *outputting* a `decimal`, then this isn't really that much of an improvement over the current situation. I mean, it's still something I would support, but that's the area where some help from the engine goes a VERY long way. You're probably also going to need a way for a user to grab certain constants to a given precision. I would think e and pi at the least. I have a lot of experience working on this problem space in PHP, and am definitely willing to help. I looked into doing a libmpdec PHP integration several years ago, but decided that voters were unlikely to give it a fair shot, and so decided against it. If you're willing to try and roll the ball up the hill though, I'll definitely help you. Jordan
