From: Robert <bob.news@...>
Date: 2003-05-21T06:54:22+09:00
Subject: Re: Ruby reference recommendations


"Marcin 'Qrczak' Kowalczyk" <qrczak@knm.org.pl> schrieb im Newsbeitrag
news:200305202113.47799.qrczak@knm.org.pl...
> Dnia wto 20. maja 2003 18:53, Robert Klemme napisa�:
>
> > Since there is no way in Java to define a class a having immutable
> > instances
>
> There is: just don't provide any method which changes attributes.
> A pity that an attribute can't be exposed read-only.

Well, but this is no strict class level declaration (like "abstract" is)
that could be used to automatically detect immutability of a class.  In Java
a compiler could evaluate all fields and if they are final assume
immutability.  But then there's still inheritance...  In Ruby I guess it
would be more complicated, because the code of a class can change all the
time.

> > IMHO the approach taken in Java (and in Ruby also) is the most
> > reasonable one.
>
> The flaw in the Java approach is that there is no single operation which
is
> both definable for user classes (and defined for classes like string to
> compare contents) and works for int (and other primitive types).

Yepp!

    robert