Are there any significant differences between blocks in Ruby vs Groovy?

Question

I've gotten used to blocks in Ruby and would like to use them in Java. Groovy seems to offer a similar feature but I don't know enough about Groovy to understand whether there are any significant differences in syntax and functionality.

Is a Ruby block equivalent to a Groovy block?

Answer 1

Not 100%. Ruby blocks require you to name all your parameters (as far as I know). A block in Groovy that doesn't specify parameters has one implied parameter, it.

Answer 2

A block is in a sense just an anymonous function. I have never programmed java, but here are some code samples for other languages to show you that blocks are similar to passing anonymous functions.

Ruby:

def add_5
  puts yield + 5
end

add_5 { 20 }
# => 25

Javascript:

var add_5 = function(callback){
  return callback.call() + 5;
}

add_5(function(){ return 20 });
// returns 25

Lua:

local function add_5(callback)
  print(callback() + 5);
end

add_5(function()
  return 20;
end)
-- returns 25

In other words, if Java supports anonymous functions like that, you got yourself a block! As they're functions, they can take arguments, just like blocks. Here's another Lua example:

local function add_something(callback)
  callback(5 / 2);
end

add_something(function(a)
  print(a + 5);
end)
-- 7.5

Answer 3

I'm not 100% familiar with Ruby, but I think the answer is no. Have a look at the doc.