Static class initializer in PHP

Question

I have an helper class with some static functions. All the functions in the class require a ‘heavy’ initialization function to run once (as if it were a constructor).

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Answer 1

NOTE: This is exactly what OP said they did. (But didn't show code for.) I show the details here, so that you can compare it to the accepted answer. My point is that OP's original instinct was, IMHO, better than the answer he accepted.

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Given how highly upvoted the accepted answer is, I'd like to point out the "naive" answer to one-time initialization of static methods, is hardly more code than that implementation of Singleton -- and has an essential advantage.

final class MyClass  {
    public static function someMethod1() {
        MyClass::init();
        // whatever
    }

    public static function someMethod2() {
        MyClass::init();
        // whatever
    }


    private static $didInit = false;

    private static function init() {
        if (!self::$didInit) {
            self::$didInit = true;
            // one-time init code.
        }
    }

    // private, so can't create an instance.
    private function __construct() {
        // Nothing to do - there are no instances.
    }
}

The advantage of this approach, is that you get to call with the straightforward static function syntax:

MyClass::someMethod1();

Contrast it to the calls required by the accepted answer:

MyClass::getInstance->someMethod1();

As a general principle, it is best to pay the coding price once, when you code a class, to keep callers simpler.

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Of all the answers (including this one), I prefer Victor Nicollet's answer. Simple. No extra coding required. No "advanced" coding to understand. (I recommend including FrancescoMM's comment, to make sure "init" will never execute twice.)

So I could have not bothered to write this answer. But so many people upvoted the accepted answer, that I conclude some people are simply not aware of the obvious, "naive", approach (that I show here). Understand this as a starting point.