[Caml-list] alloc_final and local value variables

[Caml-list] alloc_final and local value variables

[Neil Conway]

In Chapter 12 of the O'Reilly book on Ocaml, section "Creating and modifying
Objective CAML values from C", this example code is given for wrapping a
heap-allocated chunk of memory in an Ocaml value:

value create (value s)
{
  value block ;
  block = alloc_final (2, finalize_it,Int_val(s)*sizeof(IntTab),100000) ;
  Field(block,1) = (value) alloc_it(Int_val(s)) ;
  return block ;
}

This code uses a "value" local, but doesn't declare it with one of the
CAMLlocalN variables, as the Ocaml Manual says is necessary (Ocaml Manual,
"Interfacing C with Objective Caml", Section 18.5.1, Rule 2). Is this code
above correct?

Thanks in advance,

Neil

P.S. I'm aware that custom blocks are now available, but alloc_final does
everything I need...

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Re: [Caml-list] alloc_final and local value variables

[John Max Skaller]

Neil Conway wrote:

> In Chapter 12 of the O'Reilly book on Ocaml, section "Creating and modifying
> Objective CAML values from C", this example code is given for wrapping a
> heap-allocated chunk of memory in an Ocaml value:
 
> This code uses a "value" local, but doesn't declare it with one of the
> CAMLlocalN variables, as the Ocaml Manual says is necessary (Ocaml Manual,
> "Interfacing C with Objective Caml", Section 18.5.1, Rule 2). Is this code
> above correct?

CAMLlocalN et al are for beginners.

They potentially waste time making things roots that don't
need to be. Best not to use them, just learn how the
collector works .. which you need to interface with it
anyhow :-)

-- 
John Max Skaller, mailto:skaller@ozemail.com.au
snail:10/1 Toxteth Rd, Glebe, NSW 2037, Australia.
voice:61-2-9660-0850


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