CODEWITHSUNDEEP
phpvariablesstaticdoublequotes
Chris
Chris

Reputation: 1262

PHP static properties in double quotes

How can I get PHP to evaluate a static variable in double quotes?

I want to do something like this:

log("self::$CLASS $METHOD entering");

I've tried all sorts of {} combos to get the variable value of self::$CLASS, but nothing has worked. I've currently settled with string concatenation but it is a pain to type:

log(self::$CLASS . " $METHOD entering");

Upvotes: 49

Views: 26290

Answers (8)

arvil
arvil

Reputation: 920

I find it odd that noone has suggested the sprintf function yet.

say:

<?php

class Foo {
    
    public static $a = 'apple';

}

you would use it with:

echo sprintf( '$a value is %s', Foo::$a );

so on your example its:

log(
    sprintf ( ' %s $METHOD entering', self::$CLASS )
);

Upvotes: 2

Szczepan Hołyszewski
Szczepan Hołyszewski

Reputation: 3175

Use an anonymous identity function stored in a variable. This way you will have $ immediately after {:

$I = function($v) { return $v; };
$interpolated = "Doing {$I(self::FOO)} with {$I(self::BAR)}";

(I am using class constants in this example but this will work with static variables too).

Upvotes: 7

Frank
Frank

Reputation: 2041

<?php

class test {
    public $static = 'text';
    public $self = __CLASS__;
    // static Method
    static function author() {
        return "Frank Glück";
    }
    // static variable
    static $url = 'https://www.dozent.net';
    public function dothis() {
       $self = __CLASS__;
       echo <<<TEST
           
           {${!${''}=static::author()}} // works
           {$self::author()}            // works
           {$this->self::author()}      // do/don't works but with notice
           ${!${''}=self::author()}     // works
           
           {${$this->self}}::author()}} // do/don't works but with notice
           ${${self::author()}}         // do/don't works but with notice
           ${@${self::author()}}        // works but with @ !
           
TEST;
    }
}

$test = 'test'; // this is the trick, put the Classname into a variable

echo "{$test::author()} {$$test::$url}";
echo <<<HTML
<div>{$test::author()}</div>
<div>{$$test::$url}</div>
HTML;

$test = new test();
$test->dothis();

Output for 8.2.14 - 8.2.17, 8.3.0 - 8.3.4:

Deprecated: Using ${expr} (variable variables) in strings is deprecated, use {${expr}} instead in /in/uGdhi on line 18

Deprecated: Using ${expr} (variable variables) in strings is deprecated, use {${expr}} instead in /in/uGdhi on line 21

Deprecated: Using ${expr} (variable variables) in strings is deprecated, use {${expr}} instead in /in/uGdhi on line 22
Frank Glück https://www.dozent.net<div>Frank Glück</div>
<div>https://www.dozent.net</div>
Warning: Undefined variable $test in /in/uGdhi on line 21

Warning: Undefined variable $Frank Glück in /in/uGdhi on line 22
           
           Frank Glück // works
           Frank Glück            // works
           Frank Glück      // do/don't works but with notice
           Frank Glück     // works
           
           ::author()}} // do/don't works but with notice
           Frank Glück         // do/don't works but with notice
           Frank Glück        // works but with @ !

Output for 8.1.0 - 8.1.27 (and older)

Frank Glück https://www.dozent.net<div>Frank Glück</div>
<div>https://www.dozent.net</div>
Warning: Undefined variable $test in /in/uGdhi on line 21

Warning: Undefined variable $Frank Glück in /in/uGdhi on line 22
           
           Frank Glück // works
           Frank Glück            // works
           Frank Glück      // do/don't works but with notice
           Frank Glück     // works
           
           ::author()}} // do/don't works but with notice
           Frank Glück         // do/don't works but with notice
           Frank Glück        // works but with @ !

Upvotes: 1

Wadih M.
Wadih M.

Reputation: 13462

The way I've accomplished it is by setting a variable to the static class itself:

$self = self::class;

Then I can interpolate it:

$string = "This is: {$self::property}";

Upvotes: 1

ali saebifar
ali saebifar

Reputation: 21

//define below
function EXPR($v) { return $v; }
$E = EXPR;

//now you can use it in string
echo "hello - three is equal to $E(1+2)";

Upvotes: 0

micropro.cz
micropro.cz

Reputation: 616

Unfortunately there is no way how to do this yet. Example in one of answers here will not work, because {${self::$CLASS}} will not returns content of self::$CLASS, but will returns content of variable with name in self::$CLASS.

Here is an example, which does not returns myvar, but aaa:

$myvar = 'aaa';
self::$CLASS = 'myvar';
echo "{${self::$CLASS}}";

Upvotes: 10

isaax2
isaax2

Reputation: 29

Yes this can be done:

log("{${self::$CLASS}} $METHOD entering");

Upvotes: -5

Electro
Electro

Reputation: 3084

Sorry, you can't do that. It only works for simple expressions. See here.

Upvotes: 49

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