Best practices for static constructors

Question

I want to create an instance of a class and call a method on that instance, in a single line of code.

PHP won\'t allow calling a method on a regular constructor:

Answer 1

Static constructors (or "named constructors") are only beneficial to prove an intention, as @koen says.

Since 5.4 though, someting called "dereferencing" appeared, which permits you to inline class instantiation directly with a method call.

(new MyClass($arg1))->doSomething(); // works with newer versions of php

So, static constructors are only useful if you have multiple ways to instantiate your objects. If you have only one (always the same type of arguments and number of args), there is no need for static constructors.

But if you have multiple ways of instantiations, then static constructors are very useful, as it avoids to pollute your main constructor with useless argument checking, weakening languages constraints.

Example:

start = $startTimestamp;
   $this->end   = $endTimestamp;
}

public static function fromDateTime(\DateTime $start, \DateTime $end)
{
    return new self($start->format('U'), $end->format('U'));
}

public static function oneDayStartingToday()
{
    $day = new self;
    $day->start = time();
    $day->end = (new \DateTimeImmutable)->modify('+1 day')->format('U');

    return $day;
}

}

As you can see in oneDayStartingToday, the static method can access private fields of the instance! Crazy isn't it ? :)

For a better explanation, see http://verraes.net/2014/06/named-constructors-in-php/