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Date: Sun, 28 Apr 2024 09:19:52 +0100
To: internals@lists.php.net
Subject: Re: [PHP-DEV] Proposal: Arbitrary precision native scalar type
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")



On 28 April 2024 07:02:22 BST, Alexander Pravdin <alex=2Epravdin@interi=2E=
co> wrote:
>Hello everyone=2E To continue the discussion, I'm suggesting an updated
>version of my proposal=2E


This all sounds very useful =2E=2E=2E but it also sounds like several mont=
hs of full-time expert development=2E

Before you begin, I think it will be really important to define clearly wh=
at use cases you are trying to cater for, and who your audience is=2E Only =
then can you define a minimum set of requirements and goals=2E

It seems to me that the starting point would be an extension with a decima=
l type as an object, and implementations for all the operations you want to=
 support=2E You'll probably want to define that more clearly than "anything=
 in the language which takes a float"=2E

What might seem like it would be the next step is converting the object to=
 a "native type", by adding a new case to the zval struct=2E Not only would=
 this require a large amount of work to start with, it would have an ongoin=
g impact on everyone working with the internals=2E

I think a lot of the benefits could actually be delivered without it, and =
as separate projects:=20

- Optimising the memory performance of the type, using copy-on-write seman=
tics rather than eager cloning=2E See Gina's recent thread about "data clas=
ses"=2E

- Overloading existing functions which accept floats with decimal implemen=
tations=2E Could potentially be done in a similar way to operator overloads=
 and special interfaces like Countable=2E

- Convenient syntax for creating decimal values, such as 0=2E2d, declare(d=
efault_decimal), or having (decimal) casts affecting the tree of operations=
 below them rather than just the result=2E This just needs the type to be a=
vailable to the compiler, not a new zval type - for instance, anonymous fun=
ction syntax creates a Closure object=2E=20

There may be other parts I've not mentioned, but hopefully this illustrate=
s the idea that "a native decimal type" doesn't have to be one all-or-nothi=
ng project=2E

Regards,
Rowan Tommins
[IMSoP]