Making Sense of the Text

In The Book of Ruby, Ruby source code is written like this:

def saysomething
    puts( "Hello" )
end

Often the code will be annotated with comments. Ruby comments are any text following a hash mark (#) on a single line. The comments are ignored by the Ruby interpreter. When I want to draw attention to some output that Ruby displays or to a value returned by a piece of code (even if that value is not displayed), I indicate this with this type of comment: # =>. Occasionally, when I want to draw attention to some input that the user should enter, I use this type of comment: # <=. Here is an example to illustrate these commenting conventions:

puts("Enter a calculation:" ) # Prompt user        this is a simple comment
exp = gets().chomp()          # <= Enter 2*4    comment shows data to enter
puts( eval( exp ))            # => 8     comment shows result of evaluation

When a piece of code returns or displays too much data to be shown in a single-line comment, the output may be shown like this:

This is the data returned from method #1
This is the data returned from method #2
This is the data returned from method #3

helloname.rb

When a sample program accompanies the code, the program name is shown in the margin as it is here.

Explanatory notes that provide hints or extra information are shown like this:

Note

This is an explanatory note.

More in-depth explanation of points mentioned in the text may be shown in a box like this: