Hi all,
I just wanted to share a couple of things I've found out lately. I
imagine they are well known to the experts here, but I thought maybe
there are other newbies out there that could benefit from it too.

1) Using proc in the case statement:

I find the case statement particularly elegant: especially when
there's a long list of choices I much prefer it to using if...
elsif... else... end. That said the latter offers a lot more
flexibility. Still a lot can be accomplished by using procs. For
example:

case val
when Hash
...
when lambda{|x| x.respond_to?(:to_ary) && x.length>1}
...
end

The block takes the case argument and its output (generally true or
false...) is used to decide if the branch should be run or not.

2) Passing a block to map or similar methods.

Say you have an array of numbers, and you want to invoke #abs for each
number. Rather than:
x = [1,-2,3,-4,5]
x.map{|x| x.abs}

you can use:
x = [1,-2,3,-4,5]
x.map(&:abs)

It may not seem much in this instance, but I found it a lot cleaner in
some cases, especially when there is a long chain of methods.

Hope that helped _someone_ :)

Diego