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PHP static variables in double quotes

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礼貌的吻别
礼貌的吻别 2020-11-29 08:16

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");
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9条回答
  • 小鲜肉
    2020-11-29 08:30

    I don’t know the answer to your question, but you can show the class name and method using the __METHOD__ magic constant.

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  • 耶瑟儿～
    2020-11-29 08:36 
    <?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()}      // works
           ${!${''}=self::author()}     // works
           
           {${$this->self}}::author()}} // don't works
           ${${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();
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  • 旧巷少年郎
    2020-11-29 08:37

    Just live with the concatenation. You'd be surprised how inefficient variable interpolation in strings can be.

    And while this could fall under the umbrella of pre-optimization or micro-optimization, I just don't think you actually gain any elegance in this example.

    Personally, if I'm gonna make a tiny optimization of one or the other, and my choices are "faster" and "easier to type" - I'm gonna choose "faster". Because you only type it a few times, but it's probably going to execute thousands of times.

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  • -上瘾入骨i
    2020-11-29 08:38

    Yes this can be done:

    log("{${self::$CLASS}} $METHOD entering");
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  • 时光说笑
    2020-11-29 08:45

    I know this is an old question but I find it odd that noone has suggested the [sprintf][1] 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 )
);
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  • 滥情空心
    2020-11-29 08:50

    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).

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