Proc code example

Let's begin by creating a simple proc:

full_name = Proc.new{ |first, last| first + " " + last} 

Now, I can call this in two ways:

• The first is to use the bracket syntax followed by the arguments I want to pass to it:

        p full_name["Jordan", "Hudgens"] 

• I can also use the call method to run the proc and pass in the arguments inside of parentheses:

        p full_name.call("Jordan", "Hudgens") 

Let's go back and retrace the proc process. In this code, I'm creating a new instance of Proc and assigning it to a variable called full_name. Procs can take a code block as their parameter, so we are passing two different arguments to them, namely, first and last. Since they are arguments, they go inside pipes.

I can do anything I want inside this code block; in this case, I'm simply displaying the first and last name. I can also change it to do something like printing my first name five times. To do this, I have to modify the code like this:

full_name = Proc.new{ |first| first * 5} 

We also have another way to create a proc:

full_name = Proc.new  do |first| 
    first * 5 
end 

You may notice that I'm only passing in a single argument to the proc and there is no error. This is one of the key differences between using procs versus lambdas, and we'll also dedicate an entire section to the other ways in which they're different, later in this chapter.

The preceding code will result in the same output: