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Thread-Topic: RFC: Add `final class Vector` to PHP
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Date: Fri, 17 Sep 2021 02:09:55 +0000
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Subject: RFC: Add `final class Vector` to PHP
From: tysonandre775@hotmail.com (tyson andre)

Hi internals,=0A=
=0A=
I've created a new RFC https://wiki.php.net/rfc/vector proposing to add `fi=
nal class Vector` to PHP.=0A=
=0A=
PHP's native `array` type is rare among programming language in that it is =
used as an associative map of values, but also needs to support lists of va=
lues.=0A=
In order to support both use cases while also providing a consistent intern=
al array HashTable API to the PHP's internals and PECLs, additional memory =
is needed to track keys (https://www.npopov.com/2014/12/22/PHPs-new-hashtab=
le-implementation.html - around twice as much as is needed to just store th=
e values due to needing space both for the string pointer and int key in a =
Bucket, for non-reference counted values)).=0A=
Additionally, creating non-constant arrays will allocate space for at least=
 8 elements to make the initial resizing more efficient, potentially wastin=
g memory.=0A=
=0A=
It would be useful to have an efficient variable-length container in the st=
andard library for the following reasons: =0A=
=0A=
1. To save memory in applications or libraries that may need to store many =
lists of values and/or run as a CLI or embedded process for long periods of=
 time =0A=
   (in modules identified as using the most memory or potentially exceeding=
 memory limits in the worst case)=0A=
   (both in userland and in native code written in php-src/PECLs)=0A=
2. To provide a better alternative to `ArrayObject` and `SplFixedArray` for=
 use cases =0A=
   where objects are easier to use than arrays - e.g. variable sized collec=
tions (For lists of values) that can be passed by value to be read and modi=
fied.=0A=
3. To give users the option of stronger runtime guarantees that property, p=
arameter, or return values really contain a list of values without gaps, th=
at array modifications don't introduce gaps or unexpected indexes, etc.=0A=
=0A=
Thoughts on Vector?=0A=
=0A=
P.S. The functionality in this proposal can be tested/tried out at https://=
pecl.php.net/teds (under the class name `\Teds\Vector` instead of `\Vector`=
).=0A=
(That is a PECL I created earlier this year for future versions of iterable=
 proposals, common data structures such as Vector/Deque, and less commonly =
used data structures that may be of use in future work on implementing othe=
r data structures)=0A=
=0A=
Thanks,=0A=
Tyson=