PHP : can't use method return value in write context

Question

I would think the following piece of code should work, but it doesn't:

if (!empty($r->getError()))

Where getError() is simply

    public function getError()
{
 return $this->error;
}

Yet I end up with this error:

can't use method return value in write context

What does this means? Isn't this just a read?

Thanks in advance!

Answer 1

From the PHP docs:

empty() only checks variables as anything else will result in a parse error

You cannot use empty() on a function. Instead, set the return from getError() to a variable and run empty() on that.

Answer 2

It's a limitation of empty()

Note: empty() only checks variables as anything else will result in a parse error. In other words, the following will not work: empty(trim($name)).

You'd have to change to this

$err = $r->getError();
if (!empty($err))

Answer 3

As pointed out by others, it's a (weird) limitation of empty().

For most purproses, doing this is equal as calling empty, but this works:

if ($r->getError() != '')

Answer 4

Thanks for the help!

But i don't unterstand why it's not allowed to check wheter a return value is empty or not.