From: Trans <transfire@...>
Date: 2007-03-17T02:44:21+09:00
Subject: Re: java guilt



On Mar 16, 12:45 pm, Pit Capitain <p...@capitain.de> wrote:
> Jos Backus schrieb:
>
> > On Thu, Mar 15, 2007 at 11:27:43AM +0900, David A. Black wrote:
> >> As soon as someone figures out a way to make it work, all will be well
> >> :-)  Actually the libraries that allow block-scoped core changes have
> >> never been widely used, as far as I can tell.
>
> > Are you referring to libraries like `scope-in-state'? AfaIac, these don't do
> > what I want them to do, which is the ability to restrict changes made to some
> > class while executing code in some other class. This is probably expensive as
> > hell and non-trivial to implement. But it sure would be great to have as it
> > would make Ruby a "safer" language.
>
> Jos, we've talked about this two months ago on ruby-core. Maybe it's
> only the syntax of libraries like "import-module" which you don't like,
> but I think they can do what you want. See below.
>
> > Imagine if you could add String#foo to be visible within class Bar only
> > without having to subclass String and use it inside of Bar instead of String
> > (arguably the cleanest way to make this work otherwise).
>
> Changing the interface of import-module to something like Tom's example,
> here's your use case:
>
>    require "import-module-extended"
>
>    class Bar
>
>      extending(String) do
>        def foo
>          "the foo version of #{self.inspect}"
>        end
>      end
>
>      def initialize(name)
>        @name = name
>      end
>
>      def hello(name = nil)
>        name ||= @name
>        puts(name.foo)
>      end
>
>    end
>
>    b = Bar.new("Jos")
>    b.hello                         # => the foo version of "Jos"
>    b.hello("Pit")                  # => the foo version of "Pit"
>
>    b.hello(1) rescue puts "no Fixnum#foo"  # => no Fixnum#foo
>    "Pit".foo rescue puts "no String#foo"   # => no String#foo

I stand corrected. This is a fine interface.

T.