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Thread-Topic: [PHP-DEV] Adding `final class Deque` to PHP
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Subject: Re: [PHP-DEV] Adding `final class Deque` to PHP
From: tysonandre775@hotmail.com (tyson andre)

Hi Levi Morrison,=0A=
=0A=
> > "Maximum size" shouldn't be an issue for `Deque` specifically, it's a `=
size_t`. It isn't an issue for SplFixedArray and ArrayObject.=0A=
> > (or for=0A=
> > PHP would just encounter a fatal error due to either=0A=
> =0A=
> You wrote a lot, but unfortunately it was based on a misunderstanding.=0A=
> In some languages you can set the maximum allowed number of items a=0A=
> specific Deque can hold. For example (pseudo-code):=0A=
> =0A=
> =A0=A0=A0 let deque =3D new Deque<int>(max_capacity: 3)=0A=
> =A0=A0=A0 deque.push_back(1)=0A=
> =A0=A0=A0 deque.push_back(2)=0A=
> =A0=A0=A0 deque.push_back(3) # okay, it's now full=0A=
> =0A=
> =A0=A0=A0 deque.push_back(4) # !=0A=
> =0A=
> In this condition, they either error or remove the earliest.=0A=
> =0A=
> It's okay if the proposed Deque doesn't add this capability, but it's=0A=
> the only remaining major functionality which some languages have but=0A=
> not the others; it should at least be discussed, I think.=0A=
=0A=
Oh, I hadn't remembered seeing that before. That makes sense.=0A=
All of the implementations I'd remembered were unlimited.=0A=
(https://cplusplus.com/reference/deque/deque/max_size/ was a system limit, =
for example)=0A=
=0A=
I can't think of a common use case for that in php.=0A=
If there was one, though, I strongly believe it shouldn't be the same class=
 (and shouldn't be a subclass),=0A=
in order to ensure the behavior of push or other operations remains easy to=
 reason about.=0A=
This can be done in userland as a userland class.=0A=
=0A=
- (e.g. with a Deque instance property and runtime `count() < $this->maxCap=
acity` checks,=0A=
  to choose their own desired return value or Throwable subclass (or manual=
 array and circular buffer in PHP)=0A=
=0A=
Thanks,=0A=
Tyson=0A=