What does the PHP syntax $var1->$var2 mean?

Question

What is the explanation for the following syntax?

$var1->$var2 // Note the second $

Answer 1

$var1 is an object.

$var2 is (possibly) the name of a variable inside $var1.

If $var2="test"; this is evaluated to:

$var1->test;

You can do this with all sorts of things:

$test = array();
$name="test";
print_r($$name); // Prints array();

$test = new stdClass;
$test->hello = "hi";
$name2="hello";
echo $test->$name2; // Echos hi

You can even get really fancy:

echo $$name->$name2; // Echos hi