Re: [Caml-list] Preventing values from escaping a context

[Goswin von Brederlow <goswin-v-b@web.de>]

Rich Neswold <rich.neswold@gmail.com> writes:

> On Wed, Feb 10, 2010 at 2:55 AM, Goswin von Brederlow <goswin-v-b@web.de>
> wrote:
>
>     Why not make the context a custom block with finalizer? The finalizer
>     then frees the resources. If the context escapes then it remains alive
>     and the finalizer will not be called any time soon. Only when it is no
>     longer reachable. That would also allow someone to create a context
>     and use it for a number of operations before forgeting it.
>
>
> Good point. I'll need to consider this as a possible API direction. I have many
> years of C/C++ programming under my belt, so I tend to want to micromanage the
> resources. :)

As an example I have done this while rewriting Unix.file_descr for
myself.

My FD is a custom block containing the int. MyUnix.close will set the
int to -1 to signal the FD is no longer valid. MyUnix.read / write /
... throw an exception when the FD is -1. And the finalizer outputs a
warning and closes the FD unless it is -1.

That way I can close FDs when I want them closed and I can not leak an
unclosed FD (although you can still keep it alive forever). I also get a
warning when I forget to close an FD either soon after it dies or at the
end of the program if it was kept alive forever.

MfG
        Goswin