Use JavaScript-like "with" syntax in Ruby

JavaScript has "with" syntax. At first, I write a code without "with".

console.log(Math.cos(1/2)); //=> 0.8775825618903728
console.log(Math.sqrt(2)); //=> 1.4142135623730951

Then, I write with "with".

with(Math) {
  console.log(cos(1/2)); //=> 0.8775825618903728
  console.log(sqrt(2)); //=> 1.4142135623730951
}

On the other hand, Ruby has not "with" syntax.

puts Math.cos(1/2) #=> 1.0
puts Math.sqrt(2) #=> 1.4142135623731

Look! I can use "with" in Ruby!

with(Math) {
  puts cos(1/2) #=> 1.0
  puts sqrt(2) #=> 1.4142135623731
}

To do this, I wrote "with" function.

def with(obj, &block)
  obj.instance_eval(&block)
end

So, I can use "with" syntax.

with(Math) {
  puts cos(1/2) #=> 1.0
  puts sqrt(2) #=> 1.4142135623731
}

Of course, other type of object is OK. String, Intger and so on.

with("I love Ruby.") {
  puts reverse #=> .ybuR evol I
  puts gsub(/Ruby/, "YUI") #=> I love YUI.
}

with(1) {
  puts succ #=> 2
}