如何从对象而不是其类访问常量？

Question

I need to access a constant that belongs to a class, but instead of writing the class' name explicitly, I want to retrieve it from the object directly. The object is a property of another object.

$this->fetcher::BASE_URL

This statement produces the error syntax error, unexpected '::' (T_PAAMAYIM_NEKUDOTAYIM)

Answer 1

Here's an ugly work-around....

<?php
class simpleClass {
    public function __construct() {
        $this->fetcher = new simpleClass2();
    }

    public function printBaseURL() {
        $fetcher = $this->fetcher;
        print 'Base URL: ' . $fetcher::BaseUrl;
    }
}

class simpleClass2 {
    const BaseUrl = 'one';
}


$simpleClass = new simpleClass();

$simpleClass->printBaseURL();

Answer 2

You could use a function to return the constant

class MyClass
{
   function getConstant() {
       return  self::CONSTANT . "\n";
   }
}

Then call that function

$class = new MyClass();
$class->getConstant();

Or simply call the constant

MyClass::CONSTANT;

You can find more information about accessing constants within classes here . Look at the "user contributed notes", very good examples with explanation there.