Sometimes I find myself saying: “must be a better way to do this”. And sometimes, there are :-)

This is the case of processing the elements of a list. Let’s see it in an example:

I have a object shop_list which is a string with a list of element separated by comas

1
2

1.9.3-p0 :002 > shop_list
 => "oranges, eggs, oat, water"

when I split them I get:

1
2

1.9.3-p0 :003 > shop_list.split(',')
 => ["oranges", " eggs", " oat", " water"]

But some of the new elements of the list have a space before them. And I need the list with no spaces to send it to another object, method, app or whatever which doesn’t like those extra spaces. I can remove them like this:

1
2

1.9.3-p0 :004 > shop_list.split(',').map { |e| e.strip }
 => ["oranges", "eggs", "oat", "water"]

But at Ruby 1.9 we have a simpler way to do the same and is more concise:

1
2

1.9.3-p0 :005 > shop_list.split(',').map(&:strip)
 => ["oranges", "eggs", "oat", "water"]

So this:

1
2
3
4

# name_args = "oranges, eggs, oat, water"
shop_list = name_args.split(',').map do |item|
  item.strip
end

is the same as this:

1
2

# name_args = "oranges, eggs, oat, water"
shop_list = name_args.split(',').map(&:strip)

The reason is because there is a method called to_proc that convert an object prefixed with an ampersand (&) in a method to call. Ruby will see the symbol (:strip) and it will try to convert it into a Proc to call the block with the list from the map and invoking the method strip at each one of the elements from the list.

Ok, this is not the best explanation ever but I like the new concise form :-)