From: James Edward Gray II <james@...>
Date: 2007-08-26T12:17:36+09:00
Subject: Re: IRB module with non-blocking asynchronous gets

On Aug 25, 2007, at 3:09 AM, Shane Liesegang wrote:

> Is there a way to use the IRB module so that it evaluates code on- 
> demand
> only instead of running in a constant loop?

I'm working on my glue code speech for Lone Star Rubyconf today so my  
first thought was:

#!/usr/bin/env ruby -wKU

class IRbOnDemand
   def initialize
     @irb = IO.popen("irb -f --simple-prompt --noreadline", "r+")
   end

   def run(ruby)
     @irb.puts ruby
     @irb.flush

     @irb.each do |line|
       return eval($1) if line =~ /\A=>\s*(.+)/
     end
   end
end

irb    = IRbOnDemand.new
result = irb.run %Q{a = %w[words] * 3}
puts "Result:  #{result.inspect}"

puts "Doing other things..."
sleep 3

result = irb.run %Q{a}
puts "Result:  #{result.inspect}"

__END__

Is that what you are after?  If it is, do we really need IRb at all?   
How's this:

#!/usr/bin/env ruby -wKU

class IRbOnDemand
   def initialize
     @binding = binding
   end

   def run(ruby)
     eval ruby, @binding
   end
end

irb    = IRbOnDemand.new
result = irb.run %Q{a = %w[words] * 3}
puts "Result:  #{result.inspect}"

puts "Doing other things..."
sleep 3

result = irb.run %Q{a}
puts "Result:  #{result.inspect}"

__END__

James Edward Gray II