In certain other languages (AS3 for example), it has been noted that initializing a new array is faster if done like this var foo = [] rather than var foo = new Array() for reasons of object creation and instantiation. I wonder whether there are any equivalences in PHP?
class Foo {
private $arr = array(); // is there another / better way?
}
分享 In ECMAScript implementations (for instance, ActionScript or JavaScript), Array() is a constructor function and [] is part of the array literal grammar. Both are optimized and executed in completely different ways, with the literal grammar not being dogged by the overhead of calling a function.
PHP, on the other hand, has language constructs that may look like functions but aren't treated as such. Even with PHP 5.4, which supports [] as an alternative, there is no difference in overhead because, as far as the compiler/parser is concerned, they are completely synonymous.
// Before 5.4, you could only write
$array = array(
"foo" => "bar",
"bar" => "foo",
);
// As of PHP 5.4, the following is synonymous with the above
$array = [
"foo" => "bar",
"bar" => "foo",
];
If you need to support older versions of PHP, use the former syntax. There's also an argument for readability but, being a long-time JS developer, the latter seems rather natural to me. I actually made the mistake of trying to initialise arrays using [] when I was first learning PHP.
This change to the language was originally proposed and rejected due to a majority vote against by core developers with the following reason:
This patch will not be accepted because slight majority of the core developers voted against. Though if you take a accumulated mean between core developers and userland votes seems to show the opposite it would be irresponsible to submit a patch witch is not supported or maintained in the long run.
However, it appears there was a change of heart leading up to 5.4, perhaps influenced by the implementations of support for popular databases like MongoDB (which use ECMAScript syntax).
分享
