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Date: Wed, 30 Dec 2020 12:36:30 -0700
Message-ID: <CAK70goOwL-mQhDbCRa+tAt+zBv=Ot+vXxOCeTEqD+00xx1L-kA@mail.gmail.com>
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Analysis of property visibility, immutability, and
 cloning proposals
From: cja987@gmail.com (Chuck Adams)

On Wed, Dec 30, 2020 at 12:27 PM Larry Garfield <larry@garfieldtech.com> wr=
ote:
>
> If you clone the object, you don't duplicate 15+1 zvals.  You duplicate j=
ust the one zval for the object itself, which reuses the existing 15 intern=
al property entries.  If in the new object you then update just the third o=
ne, PHP then duplicates just that one internal zval and modifies the new on=
e.  So you still are using only 18 zvals, not 36 zvals.  (Engine people: Ye=
s, I am *very* over-simplifying.  I know.)
>

I've pondered hacking in something like perl's bless() to turn arrays
into value objects, but according to this it looks like an object with
clone-on-write behavior would be better, as I'm assuming arrays do a
full shallow copy: given an array of 15 entries, pass it to a
function, change one member, now you're using 15 more zvals, as
opposed to just one with an object.

Am I reading that right?

--c