Calling Array Key on Assigned Function Returned Array?

Question

From PHP 5.4, I can call an element of a function returned array, like so: func()['el'].

I'm running PHP 5.6 and test the following (simplified) code:

Works

$decoded = json_decode($content, true)['foo'];

Doesn't Work

($decoded = json_decode($content, true))['foo']; // syntax error ['

I don't understand why I cannot assign json_decode($content, true) to $decoded and call the element foo immediately. This works fine in php 7

Why this is Interesting?

My PhpStorm 2017.2.1, with applied php 5.6 DOESN'T detect this code as available in PHP 7 only!

cannot reproduce : 3v4l.org/b8Q0R. You might not be running the php version you think you are. — Calimero
– Calimero, Commented Oct 4, 2017 at 8:07
I think your json $content has some issue, can you share $conent — shashi
– shashi, Commented Oct 4, 2017 at 8:10
($decoded = json_decode($content, true))['foo']; syntax is not correct for 5.6. have a look at 3v4l.org/v3Tqt — Chetan Ameta
– Chetan Ameta, Commented Oct 4, 2017 at 8:12
@ChetanAmeta I know, but that's the last part of my question — schellingerht
– schellingerht, Commented Oct 4, 2017 at 8:21

iainn · Accepted Answer · 2017-10-04 08:19:31Z

3

One of the many features that PHP 7 introduced was an Abstract Syntax Tree. This directly led to more complex expressions being possible, such as the one in your question.

Simply, the change is that a function return wrapped in brackets previously did not behave the same as one that is not:

<?php
function foo() { return ['a' => 'b']; }

echo foo()['a']; // Works in PHP 5.4+
echo (foo())['a']; // Works in PHP 7+

Functional array dereferencing, as you mention, was added in 5.4, but only as a special case in the parser. In PHP 7+, you can dereference any expression that yields an array.

answered Oct 4, 2017 at 8:19

iainn

17.4k9 gold badges38 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Calling Array Key on Assigned Function Returned Array?

Works

Doesn't Work

Why this is Interesting?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Works

Doesn't Work

Why this is Interesting?

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related