> On 20 Nov 2014, at 09:34, Rowan Collins <rowan.coll...@gmail.com> wrote:
>
> Note that there are many, many places where expressions are actioned for
> their side effects even though the result is discarded. The following will
> increment $a 3 times, even though it is discarded each time:
>
> $a = 0;
> ++$a; // 1
> class Foo { function __construct() {} }
> new Foo(++$a); // 2
> function bar() {}
> bar(++$a); // 3
> class WTF {}
> new WTF(++$a); // suddenly, PHP becomes lazy
>
> Test: http://3v4l.org/tcnv63 (note that HHVM increments all 4 times; PHP 4
> only twice because class Foo has no old-style constructor)
>
> Lazy evaluation certainly has benefits, but it's not, in general, a feature
> of PHP. That it happens in this one very specific case is what is so
> unexpected.
You’re forgetting perhaps the most common and fundamental case in PHP (and C,
from which it comes): expression statements.
Any expression, followed by a semicolon, is a valid statement. The expression’s
result is discarded, but it’s always evaluated. Otherwise function calls
wouldn’t work, nor would assignment, both of which are expression statements.
--
Andrea Faulds
http://ajf.me/
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