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You have completed Ruby Basics!
You have completed Ruby Basics!
Preview
We've shown you how to call methods that Ruby defines for you. Now let's learn how to define your own methods.
- Defining a method
-
defkeyword - method name
- method body: one or more lines of code that will be run when method is called
- lines of method body are usually indented to make it clear they're a part of the method, although this isn't required
-
endkeyword
-
def wait
puts "Waiting..."
sleep 3
puts "Done"
end
def count_to_three
puts 1
puts 2
puts 3
end
- Valid method names
- All lower case
- Numbers are legal but rarely used
- Separate words with underscores. This is called snake case because it makes the name look like it's crawling on the ground.
- Call a method by typing its name in your code
count_to_three
wait
- Can call a method as many times as we want
count_to_three
count_to_three
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Here I've created another file named
temp.rb that contains some new Ruby code.
0:00
Lines 1, 2, and 3 display a message
that we're waiting, pause for
0:04
3 seconds, and then print another
message that we're done waiting.
0:08
Lines 4, 5, and 6 count from 1 to 3.
0:13
These are two separate tasks in the same
program, but it's hard to tell at a glance
0:17
which lines belong to which task, or
what task they're supposed to be doing.
0:21
It's easy to define your
own methods in Ruby.
0:26
You start with the def keyword, short for
0:28
define, followed by the name
of the method you want.
0:31
So let's create a new
method here named wait.
0:34
And next we're going to need
a method body, that's one or
0:37
more lines of code that will be
run when the method is called.
0:39
The lines of a method body are usually
indented to make it clear that they're
0:43
part of the method, although this isn't
required by the Ruby interpreter itself.
0:47
But it's a very common standard practice.
0:51
I would definitely recommend
indenting your method lines.
0:53
So we're just going to take these
first three lines of existing code and
0:56
put them inside a wait method.
1:00
The end of the method is
marked by the end keyword.
1:02
And the end keyword should be aligned
with the def keyword at the start of
1:07
the method.
1:10
So we'll convert those first three
lines of code to a wait method.
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And now let's define a count_to_three
method to hold the remaining code.
1:15
We'll just take those
existing lines of code and
1:25
indent them to form the body
of the second method.
1:27
And again,
we'll end the method with the end keyword.
1:31
You don't get to use just any
character you want in a method name.
1:34
Generally speaking,
method names should be all lowercase.
1:38
You can add numbers into them, but those
are rarely used, so try to avoid that.
1:41
If there are multiple
words in your method name,
1:45
you should separate them
with underscore characters.
1:47
This style is called snake case,
1:51
because it makes the name look
like it's crawling on the ground.
1:53
Now that we've defined the methods,
we need to call them so
1:56
that they're actually executed.
1:58
We do that just like we did
the predefined methods,
2:00
we simply type the name
of the method to call it.
2:03
So count_to_three will call the
count_to_three method that we've defined,
2:05
and wait will call the wait
method that we've defined.
2:11
Let's hit Command + S to save that,
Ctrl + S if you're on Windows.
2:16
And click down in the console
area to try running it again.
2:21
Up arrow to bring up the previous command.
2:25
And you can see that our call to
count_to_three causes the count_to_three
2:29
method to run and
print the numbers 1, 2 and 3.
2:33
And then the call to wait causes the wait
method to run and print the message,
2:36
waiting, then sleep for 3 seconds,
and then print the message, done.
2:43
We can call a method during
a program as many times as we want.
2:47
So let's add a couple additional
calls to count_to_three down here.
2:50
I'll just copy the first call and paste
it in a couple more times, save my work.
2:54
And re-run it from the console.
3:01
And you can see that it
calls count_to_three once.
3:03
It calls wait once and then it calls
count_to_three two more times down here.
3:07
Now that we understand method
calls a little bit better,
3:13
let's go back to our widgets.rb file
by clicking on it here on the side bar.
3:15
And let's implement our
welcome message to the user.
3:21
We can do that with the single
call to the puts method.
3:23
We'll pass it a string with the message,
Welcome to the widget store!,
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close the string with a pair of
double quotes and save that.
3:33
And then click down here
in the console to run it.
3:39
We do that with ruby widgets.rb.
3:42
And you can see that it prints our
welcome to the widget store message.
3:48
Our program is displaying
a welcome message to the user.
3:53
We can cross the first
requirement off our list.
3:56
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