CODEWITHSUNDEEP
phparrayskey-value
Gregor Weber
Gregor Weber

Reputation: 688

Reference an arrays key in its value

I know this seems like something that should be averted by design, but let's just say it is bitterly needed: Is it possible to reference the key belonging to a value while it is being initialized?

Here is what I imagine it to be (not exactly the case in which I need it, but the key is primitive as well):

$array = array(25 => "My key is " . $this->key);

I need this because the array key is used in each value. Actually the value is another array which has a value in which the first array key is used. Like I said in the comments, I want to keep it DRY. Doing it is no problem, but I want to do it good ;)

Upvotes: 1

Views: 127

Answers (2)

Artem L
Artem L

Reputation: 10253

If you are writing an array yourself you can just put key value to array value like:

$array = array(25 => "My key is 25");

If you are have an array already you can use a foreach and add all keys to it's values:

foreach($array as $key => $value) {
    $array[$key] = sprintf('%s %s', $value, $key);
}

Or if you just want to have an array of keys of existing array you can use either array_flip if you want to maintain key=>value, but have keys and values flipped. Or you can use array_keys if you want just an array of keys.

To make what you want: initialize an array somewhere and do not add any keys to it's value you can implement ArrayAccess, Countable and have:

public function offsetGet($offset) {
    return isset($this->container[$offset]) 
                ? $this->container[$offset] . ' ' . $offset 
                : null;
}

or something like this. But in this case you need to have a variable that contains this array to be an instance of your ArrayAccess implementation. And depending of usage of this class you probably will need to implement more interfaces.

Upvotes: 1

ThiefMaster
ThiefMaster

Reputation: 318478

No, there is no way to reference the key when defining the value. Except maybe writing a preprocessor that embeds it in the string. But that would only work for primitive values.

Upvotes: 0

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