Using $this when not in object context with ReflectionFunction->invoke()

Question

class someClass {
    private $success = "success\n";
    function getReflection() {
        return new ReflectionFunction(function() {
            print $this->success;
        });
     }
}
$reflection = (new someClass)->getReflection();
$reflection->invoke();

When I run this, I get a

Fatal error: Using $this when not in object context in Command line code on line 5

What's happening here? Why is $this not defined there...?

As I'm in a Closure inside a method, $this normally should be defined. And yes, I'm on a newer version than PHP 5.4.

How can I fix it?

bwoebi · Accepted Answer · 2016-06-30 13:22:00Z

5

ReflectionFunction is operating on unbound Closures. That's why after the ReflectionFunction::invoke() call, there's no defined $this variable inside the Closure and as such your fatal error appears.

But there's a way around it.

ReflectionFunction offers you three necessary methods to call it with the $this binding:

ReflectionFunctionAbstract::getClosure()
ReflectionFunctionAbstract::getClosureThis()
ReflectionFunctionAbstract::getClosureScopeClass()

The ReflectionFunctionAbstract::getClosure() is still unbound, but we can bind it via Closure::bind().

All Closure::bind() needs is the Closure, the wished object to be bound to and the class scope.

Then the solution is:

call_user_func(\Closure::bind(
    $reflection->getClosure(),
    $reflection->getClosureThis(),
    $reflection->getClosureScopeClass()->name));

I initially wanted to post this as a question only, but I had found the solution myself just before posting, so just adding the answer. Context was this issue: https://github.com/rdlowrey/Auryn/pull/72

edited Jun 30, 2016 at 13:22

answered Oct 26, 2014 at 0:56

bwoebi

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1 Comment

Kevin Bond Over a year ago

Just want to add this was a PHP bug that got fixed in PHP 7.2.12+. The code in the original question works as of 7.2.12.

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