Re: [Ocaml-lib-devel] Base 64 encode/decode

[Nicolas C. <war...@fr...>]

> On Fri, 9 Apr 2004, Nicolas Cannasse wrote:
>
> A couple of questions:
>
> > external unsafe_char_of_int : int -> char = "%identity"
>
> Is this really any faster than using the pervasives char_of_int?

%identity means it's removed at compile time, it's just a typed Obj.magic.
on the other side you have :

let char_of_int n =
    if n < 0 || n > 255 then invalid_arg "char_of_int" else
unsafe_char_of_int n

> > let inv_chars =
> >  let a = Array.make 256 (-1) in
> >  for i = 0 to 63 do
> >   Array.unsafe_set a (int_of_char (Array.unsafe_get chars i)) i;
>
> Likewise- especially since this code will be executed only once (on module
> load), is unsafe_set worthwhile to call?
>
> >   let c = int_of_char (String.unsafe_get s i) in
>
> Ditto & etc.

It's always better to use unsafe when you're really sure that it will never
breaks.
IMHO, basic functions such as b64 encode/decode should be tuned to get best
performances.
As long as using unsafe_get instead of get does not break code
readability... it's worth doing.

Regards,
Nicolas Cannasse