static_or_non_static.php

<?php

/**
 * Allows a method in a class to be called either statically or instanced.
 *
 * To use, ensure custom method names are camelCase starting withthe word
 * "either". For example, a method defined as "eitherGetResults()"
 * can be called in either of the two following ways:
 *
 *   $exampleObject->getResults()
 *   ExampleClass::getResults()
 */
trait EitherMethods
{
    public static function __callStatic($methodName, $arguments)
    {
        $currentClass = get_called_class();
        $currentObject = new $currentClass;
        $newMethodName = 'either' . ucfirst($methodName);

        if (! method_exists($currentObject, $newMethodName)) {
            throw new BadMethodCallException('Call to undefined method ' . get_class($currentObject) . '::' . $methodName . '()');
        }
        return call_user_func_array([$currentObject, $newMethodName], $arguments);
    }

    public function __call($methodName, $arguments)
    {
        $newMethodName = 'either' . ucfirst($methodName);

        if (!method_exists($this, $newMethodName)) {
            throw new BadMethodCallException('Call to undefined method ' . get_class($this) . '::' . $methodName . '()');
        }
        return $this->{$newMethodName}(...$arguments);
    }
}

Example usage:

<?php

class ExampleClass
{
    use EitherMethods;

    private $list = [];

    public function eitherA()
    {
        array_push($this->list, 'a');
        return $this;
    }

    public function eitherB()
    {
        array_push($this->list, 'b');
        return $this;
    }

    public function get()
    {
        return join($this->list, ', ');
    }
}

echo ExampleClass::a()->b()->get();