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From: Brian Candler <b.candler@pobox.com>
Newsgroups: comp.lang.ruby
Subject: Re: To Yield or Not to Yield: An Inferable Question
Date: Wed, 20 Apr 2011 03:59:12 -0500
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.ruby:3225

Michael Edgar wrote in post #993395:
> If one peruses the Ruby standard library, one will find that just in the
> Ruby
> code alone, block_given? occurs 265 times, in *every single case* is
> used
> to execute yield conditionally, and in every single case, the result is
> used
> only as a simple constant. [4]

However there are some cases where this is done unnecessarily, 
net/telnet.rb being the prime example. e.g.

      if block_given?
        waitfor({"Prompt" => match, "Timeout" => time_out}){|c| yield c 
}
      else
        waitfor({"Prompt" => match, "Timeout" => time_out})
      end

could have been written simply as:

      waitfor({"Prompt" => match, "Timeout" => time_out}, &blk)

Net::Telnet also has a load of conditionals because it lets you pass an 
optional block to each call for capturing debug information - an awkward 
API to use, because often you end up passing the same block every time. 
It would have been much easier to pass this in the options hash where it 
could have been set as a default.

e.g.

  t = Net::Telnet.new("Debug" => lambda { |c| print c }, ...)
  t.cmd("foo")
  t.cmd("bar")
  t.cmd("baz")

whereas as the moment you have to write

  t = Net::Telnet.new(...)
  out = lambda { |c| print c }
  t.cmd("foo",&out)
  t.cmd("bar",&out)
  t.cmd("baz",&out)

Also, a Debug parameter could invoke the "<<" method instead of "call", 
which would make it usable with Files and Strings. Then Proc#<< could be 
aliased to call, and duck-typing would suddenly become a lot prettier. 
There would also be no need for Enumerator::Yielder either.

Sorry, I've strayed right off there :-)

-- 
Posted via http://www.ruby-forum.com/.