Object destructor is called immediately when object is removed from memory.

Object is removed from memory when it goes out of scope (eg. local variables created on the stack in C++ go out of scope when the method completes)
----
A similar effect is achieved in GarbageCollected environments with an idiom like:

    |file|
    [ file := File open: 'filename.txt'.
      self use: file.
    ] ensure: [file close].

The file will be closed in a deterministic, statically scoped way. This idiom can be generalised more by using block closures, thus:

    File
        withOpen: 'filename.txt'
        do: [:file| self use: file].

or whatever. 

----

''I have seen numerous discussions/arguments about the usefulness (or not) of DF in a garbage-collected world, or indeed whether it's possible to elegantly integrate determinism into garbage-collected languages (I'm talking about releasing memory here, not external resources/handles).  Is it really an either/or decision, or are there languages which deal with the problem (if it really is a problem) successfully?''