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Date: Thu, 2 Jun 2016 06:09:44 +1000
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To: Lester Caine <lester@lsces.co.uk>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Set object properties inline
From: me@jesseschalken.com (Jesse Schalken)

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On Wed, Jun 1, 2016 at 7:40 PM, Lester Caine <lester@lsces.co.uk> wrote:

> Morphed into simply passing an array to the constructor ...
>
>         $static1         = new Data\StaticVariable( array(
>           'name'         => 'variable name',
>           'value'        => $unknown1,
>           'functionName' => 'blahFunction' ) );
>
>         // className defaults to null
>
> Of cause the short cut at that time was to drop the names and simply
> count the variables, but what this replaces is all the complications of
> named parameters and allowed passing objects in such as '$unknown1'
>

This works fine to remove the temporary variable but compromises two things
that I think are very important:

   1. IDE tooling and static analysis. An IDE can't autocomplete property
   names as array keys, because it doesn't know the array keys are properties,
   nor can it ensure that the properties actually exist, are visible, and are
   being assigned the correct type. If I do a "Find Usages" on a property, it
   may appear to be only read and never set, implying I can remove the
   property and replace all the reads with the default value. Any static
   analysis tool would have the same trouble.
   2. Performance. The code spends time building a temporary hash table
   just to loop over it, look up each key in the object's property table,
   check visibility, check type, assign it, and discard the hash table. That's
   a lot of overhead just to assign some properties. With a dedicated inline
   property assignment syntax, a normal bunch of "assign property" bytecode
   instructions can be output and the PHP runtime will cache the property
   offsets and assign them directly, and can elide the property type check if
   the optimiser knows it will pass. HHVM can even burn the property offset
   right into the compiled machine code. That's *way *faster. (At least
   that's how I was told it works when I asked here a couple of weeks ago.)



> --
> Lester Caine - G8HFL
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