From: TRANS <transfire@...>
Date: 2007-07-09T23:29:14+09:00
Subject: Re: GetoptLong w/ DSL

On 7/9/07, Nobuyoshi Nakada <nobu@ruby-lang.org> wrote:
> Hi,
>
> At Sun, 8 Jul 2007 22:35:10 +0900,
> TRANS wrote in [ruby-core:11617]:
> >
> > On 7/8/07, nobu@ruby-lang.org <nobu@ruby-lang.org> wrote:
> >
> > > You can't change the object which is the subject of instance
> > > variables.
> >
> > what?
>
> An artificial example:
>
>   @flags = [:help, :h]
>   GetoptLong.new do
>     flag *@flags
>     required :name
>   end

Ah, I see. Yea, one would just have to know that it's an instance_eval
block by documentation.

> Well, maybe, I should have write as "against overdoing by
> hidden instance_eval".  But I'm still doubtful that "DSL" is
> standard by default.
>
> It can't be a separated library?

Sure, it can. Indeed, my first implementation was as a subclass of
GetoptLong. But being such a small bit of code that doesn't cause
backward incompatibility, and results (IMHO) in code that's easier to
read and more convenient to write, it seemed like a good addition to
GetoptLong itself.

But I'm curious. DSLs seem to be one of the great strengths of Ruby.
Why shun them in standard library?

Thanks,
T.