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Re: [Caml-list] Question about string ref and Hashtbl.
- Bob Bailey
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| Date: | -- (:) |
| From: | Bob Bailey <bobbaileyjr@y...> |
| Subject: | Re: [Caml-list] Question about string ref and Hashtbl. |
That's an interesting idea. SO the key string and the value string will really point to the same
location in memory.
So if I did (string,string ref) Hashtbl.t,
then the string ref would be a pointer to the key string.
Would that allow me to compare two string ref variables together? Would the comparason of the
locations of the strings mean I wouldn't have to do a full string compare?
so in my module
type index = string ref
type dict = (string,index) Hashtbl.t
So in the case of
let a = Hashtbl.find dict "a"
let b = Hashtbl.find dict "a"
would a==b be the same as !a == !b?
Also, would a==b be a faster comparason in this case?
thanx
bob
--- Yamagata Yoriyuki <yoriyuki@mbg.ocn.ne.jp> wrote:
> From: Bob Bailey <bobbaileyjr@yahoo.com>
> Subject: [Caml-list] Question about string ref and Hashtbl.
> Date: Fri, 19 Mar 2004 14:03:23 -0800 (PST)
>
> > type t =
> > {
> > mutable last:int;
> > names: (string,int) Hashtbl.t;
> > indexes:(int,string ref) Hashtbl.t;
> > }
>
> If I were you, I would define the dictonary as
>
> type t = (string, string) Hashtbl.t
>
> and add function as
>
> let add dict str =
> try
> Hashtbl.find dict str
> with Not_found ->
> Hashtbl.add dict str str
>
> In addition, if some of your strings become unused during exectuion,
> I would recommend useing WeakHash.
>
> module Dict = Weak.Make (struct
> type t = string
> let equal = (=)
> let hash = Hashtbl.hash
> end)
>
> and use Dict as Hasthtbl. In this way, if a string becomes unused,
> it is GC-ed and removed from the dict.
>
> --
> Yamagata Yoriyuki
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