Re: [Ocaml-lib-devel] properties of symbols

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

> Hi,
>
> under Lisp there are to very useful functions `put' and
> `get'. Emacs, C-h f put RET ->
>
> put is a built-in function.
> (put SYMBOL PROPNAME VALUE)
>
> Store SYMBOL's PROPNAME property with value VALUE.
> It can be retrieved with `(get SYMBOL PROPNAME)'.
>
> Eg:
>
> (put 'car 'ccm 1500)
> (put 'car 'color 'silver)
> (put 'car 'owner "Joe")
>
> (get 'car 'owner)
> => "Joe"
>
> This functionality is something different than hashtabels.
> A Hashtable has a type ('a,'b) Hashtbl.t and 'b is fix.
>
> With static typed OCaml it's tricky to implement put and get, but it's
> possible. I needed something like this and Alain Frisch referred me to
this
> old mail
[...]

It looks interesting, although I didn't need theses before.
Some comments :
- polymorphic is better than functors (more usable and better perfs as
Martin said)
- there should be a way to retreive all the objects from a table and all the
properties from an object
- properties should be "closures" over objects so we doesn't need 2
arguments on put/get
- better would be to have a recursive data structure so properties can
themself be objects :-)

Regards,
Nicolas Cannasse