From: Rick DeNatale <rick.denatale@...>
Date: 2006-10-27T01:33:13+09:00
Subject: Re: Pass block instead of here document?

On 10/26/06, Joel VanderWerf <vjoel@path.berkeley.edu> wrote:
> Rick DeNatale wrote:
> ...
> > But in Smalltalk if you write:
> >
> >   obj msg1;msg2
> >
> > the object referenced by obj is sent msg1 and then msg2 in sequence,
> > regardless of the value returned by obj msg1.
>
> Not quite the same, but this is something similar that's been floating
> around the ml for a while:
>
> class Object
>    def then
>      yield(self)
>      self
>    end
> end
>
> hash = Hash.new.
>   then do |h| h[1] = 2 end.
>   then do |h| h[3] = 4 end
>
> p hash
>
> That's much clunkier syntactically, but it is actually useful in one
> case: when working with classes whose #new method doesn't take a block
> that allows further configuration of the new object. For example, sockets:
>
> def socket
>    @socket ||= UDPSocket.open.then do |s|
>      s.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, true)
>      s.connect("192.168.255.255", 1234)
>    end
> end

Of course this relies on UDPSocket::open returning the new socket
rather than something else.

> It works particularly well with the ||= assignment operator.

Which in turn relies on the block evaluating to the socket as well.

It's more of a variation on Smalltalk's yourself than a cascade.

Nice nonetheless.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/