Re: S-expression I/O in Ada

[Natacha Kerensikova <lithiumcat@gmail.com>]

On Aug 1, 8:25 pm, Jeffrey Carter <spam.jrcarter....@spam.not.acm.org>
wrote:
> You might very well be able to use something like:
>
> [snip]

Thanks a lot for the example, it really looks like what I'm used to
(at least in C).

I have to admit I don't really grasp the difference between the vector
you use and the Storage_Array, but it seems I have to research it by
myself before asking here.

> If you can use unbounded strings as Brenta suggested, instead of an unbounded
> array of bytes (Storage_Element), then this would be even simpler.

Actually I'm a bit reluctant to use Ada strings for atoms, because I'm
afraid it might somehow interpret the data (e.g. locale or encoding
related stuff, or trouble with NUL inherited from C). I occasionally
include binary data in S-expressions, and while I keep it on the disk
as a text file (using hexadecimal or base-64 encoding), it is the S-
expression library's responsibility to load it into memory as the
original binary data.

On the other hand, most of my atoms are indeed strings, and Character
definition from A.1.35 looks exactly like a perfect mapping to bytes.
So if Ada strings have no issue with embedded NUL or non-graphics
character, and if binary data can be losslessly recovered once stored
into an Ada string, it could be the best type for atoms. It will
probably be a while before I reach the level of reading the Reference
Manual cover-to-cover, does anyone knows whether those "if"s are
guaranteed by the standard?


Thanks for your help,
Natacha