Concatenating DIR constant with a string as an array value which is a class member in PHP

Question

Can anyone tell me why this doesn't work? It's just a crude example of what I'm trying to do somewhere else.

$stuff = array(
    'key' => __DIR__ . 'value'
);

However, this produces an error:

PHP Parse error:  syntax error, unexpected '.', expecting ')' in /var/www/.../testing.php on line 6

Also, this works:

$stuff = array(
    'key' => "{__DIR__} value"
);

Thanks for the quick response ManseUK. In the interest of understanding my problem a little more - what does it return? I var_dump'ed it: string(26) "/var/www/../trunk" — acairns
– acairns, Commented Jan 6, 2012 at 15:17

user142162 · Accepted Answer · 2012-01-06 15:14:58Z

8

The first piece of code does not work because it's not a constant expression, as you are trying to concatenate two strings. Initial class members must be constant.

From the documentation:

[property] initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

answered Jan 6, 2012 at 15:14

user142162

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

2 Comments

acairns Over a year ago

So because __ DIR __ is the current file's location its runtime information so isn't available at compile time. Thanks Tim.

user142162 Over a year ago

@acairns: Not exactly. PHP has the value of __DIR__ when the script is being compiled, as you can see when initialising the string like: "{__DIR__} value". How you're accessing the magic constant is the only difference here, where one is seen as a constant expression and the other is not.

Damien · Accepted Answer · 2012-01-06 15:18:02Z

3

You can't use operator in a property initialization. The workaround is to use the constructor:

public function __construct()
{
  $this->stuff = array(
        'key'   =>  __DIR__ . 'value'
  );
}

From the PHP doc:

This declaration may include an initialization, but this initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

http://www.php.net/manual/en/language.oop5.properties.php

answered Jan 6, 2012 at 15:18

Damien

5,8922 gold badges31 silver badges36 bronze badges

Comments

user745235 · Accepted Answer · 2012-01-06 15:21:26Z

0

Set $stuff value on your constructor

function __construct()
{
$this->$stuff = array(
        'key'   =>  __DIR__ . 'value'
    );
}

answered Jan 6, 2012 at 15:21

user745235

Collectives™ on Stack Overflow

Concatenating DIR constant with a string as an array value which is a class member in PHP

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related