How to store ruby code blocks

Question

I want to store a "code block" in a variable to be reused, something like:

block = do
|test| puts test
end

3.upto(8) block

Can someone show me what am I doing so obviously wrong? (Or if it's just impossible)

Solution

There are many ways to do this in Ruby, one of which is to use a Proc:

foo = Proc.new do |test|
  puts test
end

3.upto(8) { foo.call("hello world") }

Read more about Procs:

• http://www.reactive.io/tips/2008/12/21/understanding-ruby-blocks-procs-and-lambdas
• http://www.skorks.com/2010/05/ruby-procs-and-lambdas-and-the-difference-between-them/

Update, the above method could be rewritten as follows:

# using lower-case **proc** syntax, all on one line
foo = proc { |test| puts test }
3.upto(8) { foo.call("hello world") }

# using lambda, just switch the method name from proc to lambda
bar = lambda { |test| puts test }
3.upto(8) { bar.call("hello world") } 

They're basically very similar methods, with subtle differences.

And finally, there are probably more elegant ways to do what I've outlined, be good to hear from anyone with a better way. Hope this helps.

Comments

[Admin]

Thanks a lot. For the link even more. Can you be so kind as to include a mention of lambdas as well? For historical purpose.

[stephenmurdoch]

@Shingetsu, I added and update with lambda, as well as a slightly simplified version of the proc approach too

[Linuxios]

@Shingetsu: Lambdas aren't historical. You should almost always use them instead of Procs. They are much more fully featured and are the standard.

[Admin]

@Linuxios by historical I mean "people who will later come see the post". I read the page and saw that lambdas make more sense.

[Linuxios]

@Shingetsu: Oh! Sorry about that. We all misinterpret sometimes.