Johannes Müller schreef:
Why does the following code
<?php
interface I {
public function a();
}
class A implements I {
public function a() {}
}
class B extends A {
}
if (is_subclass_of('A', 'I')) echo "A implements I\n";
if (is_subclass_of('B', 'I')) echo "B implements I\n";
?>
outputs:
B implements I
because B subclasses A and A implements I,
I is not a base class.
try the experiment with is_a() instead.
also you should preferablly use the instanceof syntax:
<?php
$a = new A;
$b = new B;
if ($a instanceof I)) echo "A implements I\n";
if ($b instanceof I)) echo "B implements I\n";
or use the return data from class_implements(), is_subclass_of()
specifically looks at base classes ("extends"), I'm a little surprised that it
even
returns true for interfaces at all ("implements").
I would expect the following output:
A implements I
B implements I
Johannes
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