From: "Mikael Høilund" <mikael@...>
Date: 2008-05-29T11:43:51+09:00
Subject: Bug in Method#to_proc on method with block

I seem to have found a bug in Ruby 1.9. Method#to_proc doesn't seem to  
preserve receptance of blocks. This script demonstrates it:

--8<----
class ProcTester
   def one_and_block(arg, &block)
     puts "one_and_block got arg #{arg} and block: #{block.inspect}."
     puts "Something is wrong." if block.nil?
   end
end

pt = ProcTester.new
dummy = proc { :dummy }

puts "Direct call:"
pt.one_and_block(:hi, &dummy)
puts

puts "Get Method, call"
meth = pt.method(:one_and_block)
p meth
meth.call(:hi, &dummy)
puts

puts "Convert Method to Proc, call"
proc_obj = meth.to_proc
proc_obj.call(:hi, &dummy) # This fails
--8<----

The output is:
--8<----
Direct call:
one_and_block got arg hi and block: #<Proc:0x0008afac@-:11>.

Get Method, call
#<Method: ProcTester#one_and_block>
one_and_block got arg hi and block: #<Proc:0x0008afac@-:11>.

Convert Method to Proc, call
one_and_block got arg hi and block: nil.
Something is wrong.
--8<----

One would expect the Proc object to have the same parameters, as it is  
possible to define a block parameter in Procs in 1.9:
proc do |&block|
   block.call
end.call(&dummy) # => :dummy

I asked in #ruby-lang on irc.freenode.net, and it doesn't seem to be a  
known bug.

-- 
Mikael H�ilund
http://hoilund.org/