From: Assaph Mehr <assaph@...>
Date: 2005-03-24T08:09:54+09:00
Subject: Re: Block Passing and &foo Parameters



> The advantage to something like this is if you have one function you
> want to pass to a number of things, such as lists:
>
> irb(main):016:0> a = [1,2,3]
> => [1, 2, 3]
> irb(main):017:0> b = [4,5,6]
> => [4, 5, 6]
> irb(main):018:0> func = lambda {|i| puts i}
> => #<Proc:0x0034b1b8@(irb):18>
> irb(main):019:0> a.each func
> ArgumentError: wrong number of arguments (1 for 0)
>          from (irb):19:in `each'
>          from (irb):19
>          from :0
> irb(main):020:0> b.each func

You can easily pass a lambda to somethig that expects a block - just
put another & before lambda param at the point of call:

irb(main):001:0> a = [1,2,3]
=> [1, 2, 3]
irb(main):002:0> b = [4,5,6]
=> [4, 5, 6]
irb(main):003:0> func = lambda{|i| puts i}
=> #<Proc:0x02c2d6d0@(irb):3>
irb(main):004:0> a.each &func
1
2
3
=> [1, 2, 3]