From: Charles Mills <cmills@...>
Date: 2005-01-14T05:21:17+09:00
Subject: Re: Mutable strings


Mystifier wrote:
> Hi All,
>
> Since my communications skills have be questioned on the ML, I am
trying to
> be better :)
>
>
> I saw few last posts by matz categorically saying that strings shall
be
> mutable.
>
> I have nothing against or for it as a language specification. What
interests
> me that if string are immutable, we can use strings as symbols. This
can
> bring about few important effects on VM.
>
> 1) Symbols and FixNum have few exceptions to the usual rules. Symbols
may
> not have any exceptions, since symbol and strings will be basically
same.

Symbols are immutable.  The current implementation of symbols seems
like a good one to me.  They are just a number that uniquely identifies
a string (contained in a symbol table somewhere in the interpreter).

>
> 2) Efficiency of VM will improve because Symbols and Strings can be
used
> interchangeably.
>
Ruby already uses some nice tricks for sharing memory between string
instances (and between array instances).

> 3) It might help on security, perhaps.
>
> A Mutable string class can be created for mutating strings.
>
> No, I am not trying to create another java, but as Users, how many
times
> have you mutated your strings?

Try ri String.  About 1/2 the methods change the reciever.

>
> A mailing list to discuss Vuby Specifications has been created on
Berlios
> and will be active shortly for discussions.
>
> https://developer.berlios.de/projects/vuby/
>

There are already a number of Ruby VM projects.  Many of them
relatively mature.  Perhaps you should take a look at those.
If you are writing a VM, I don't see why you would need to rewrite the
standard library, or even break the Ruby API at the C level.

-Charlie