What is a "terminated object", and why can't I call methods on it?

Question

Periodically I get this exception:

NotImplementedError: method `at' called on terminated object

on this line of code:

next if Hpricot(html).at('a')

What does this error mean? How can I avoid it?

Burnie

Does it also happen if you assign the result of Hpricot(html) to a variable before whole loop instead of performing it every time? – Sclerosis

html is the loop parameter, so I can't do it before the loop, though I could do something like doc = Hpricot(html) at the top of the loop and do doc.at('a'). I'll give this a try – Burnie

Answer 1

The library you are using makes use of a custom C extension. In the C extension, it is trying to call a method on a Ruby object which has already been garbage-collected.

This can't happen in pure Ruby, because the garbage collector will only free objects which are no longer accessible from any reference. But in C, it is possible to have a reference remaining to a Ruby object, in a place which the garbage collector doesn't check (for example, the compiler may have put a variable in a CPU register).

Jezabelle

Answer 2

It might be a linking problem. Check that you didn't link the extension twice.

Howund

By "link the extension twice", do you mean "require the extension twice"? (Isn't require designed to make sure this doesn't cause problems?) – Burnie