PHP static variables in double quotes

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

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}}";

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).