Hi,

At Sat, 24 Apr 2004 14:28:45 +0900,
Joel VanderWerf wrote in [ruby-talk:98213]:
> >   $ irb --prompt xmp
> 
>            ^^^^^^^^^^^^
> 
> That's a great feature. It would be nice if the output began with a 
> comment char '#' so that you could paste into irb (or a source file) and 
> run.

$ grep PROMPT ~/.irbrc
IRB.conf[:PROMPT][:XMP][:RETURN] = "#   =>%s\n"

$ irb --prompt xmp
class Hash
  alias << :update
end
#   =>nil
table = Hash.new {{}}
#   =>{}
table["foo"] <<= {"x"=>1}
#   =>{"x"=>1}
table["foo"] <<= {"y"=>2}
#   =>{"x"=>1, "y"=>2}
table
#   =>{"foo"=>{"x"=>1, "y"=>2}}

> >   class Hash
> >     alias << :update
> >   end
> >       ==>nil
> >   table = Hash.new {{}}
> >       ==>{}
> >   table["foo"] <<= {"x"=>1}
> >       ==>{"x"=>1}
> >   table
> >       ==>{"foo"=>{"x"=>1}}
> >   table["bar"]
> 
> Did you mean something like this?
> 
>      table["bar"] << {"y"=>2}

Just a shorthand for (table["foo"] ||= {})["x"] = 1.

-- 
Nobu Nakada