Repeated Variable at PHP 7 Null Coalescing operator

Question

Look at this code:

$this->request->data['comments']['user_id'] = 
    $this->request->data['comments']['user_id'] ?? ‘value’;

I want to check if some var is null and if the same var is null set the same var to ‘value’.

Hence I am repeating the same variable after the equal operator, this does not feels right.

So I feel that we need another operator like ??= similar to +=:

$this->request->data['comments']['user_id’] ??= ‘value’.

So if the var is null it’s set to ‘value’ and else stays the same.

@Epodax the null coalesce operator was introduced to write less code for situations like this. Remark that $var appears 3 times in your example and only 2 times in the code posted in the question. Your suggestion pushes it in the wrong direction. — axiac
– axiac, Commented Mar 8, 2016 at 12:31
@axiac - You learn something new every day, however, why not provide this as a answer / soloution for OP? It seems like it's exactly what OP needs? — Epodax
– Epodax, Commented Mar 8, 2016 at 12:36
@Epodax the null coalesce operator is what the OP uses right now. She searches for a way to write even shorter code, to write the long expression from the left hand side of the assignment ($var in your example) only once. The operator she proposes does not (yet) exist in PHP. — axiac
– axiac, Commented Mar 8, 2016 at 12:44

Midori Kocak · Accepted Answer · 2016-03-09 23:05:17Z

2

I implemented this operator and made a pull request for PHP7. Currently it's on RFC stage and if it's accepted, it is going to be merged to PHP version 7.x.

https://wiki.php.net/rfc/null_coalesce_equal_operator

answered Mar 9, 2016 at 23:05

Midori Kocak

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Comments

Alex Shesterov · Accepted Answer · 2016-03-08 12:26:45Z

0

Just create a utility function for this purpose:

function assignIfNotSet(&$variable, $value) {
    if (!isset($variable)) {
        $variable = $value;
    }
}

It will assign a value to the $variable if and only if its value is null or not set.

The function makes use of passing variables by references — see docs.

Usage:

$x = "original value";
assignIfNotSet($x, "other value");
var_dump($x); // "original value"

$y = null;
assignIfNotSet($y, "other value");
var_dump($y); // "other value"

// assuming $z wasn't previously defined
assignIfNotSet($z, "other value");
var_dump($z); // "other value"

It also works for array items and object properties. In your case:

assignIfNotSet($this->request->data['comments']['user_id'], 'value');

edited Mar 8, 2016 at 12:26

answered Mar 8, 2016 at 12:18

Alex Shesterov

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