Build a Monster Class: Part 4

Name: Build a Monster Class: Part 4
Uploaded: 2015-01-30T01:12:26Z
Duration: 169 s
Description: In this stage, we'll be working towards creating our own class that uses blocks, arrays, hashes, and more. In this video, we'll learn a neat trick about yielding to blocks.

2:49 with Jason Seifer

In this stage, we'll be working towards creating our own class that uses blocks, arrays, hashes, and more. In this video, we'll learn a neat trick about yielding to blocks.

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The following code will return the current object in context to a block:

yield self if block_given?

This is useful in cases where you would like to have access to the class inside of a block.

So we're done with our Monster program, 0:00

but I wanted to show you something really cool that you can do with blocks. 0:02

So, here we have our different actions and 0:07

we're calling them within the context of a block. 0:13

Let's just see what the last thing that we have here, okay, monster.hide. 0:16

Let's go to this hide method, and we yield to the block, 0:20

which means we're coming out of this method, and calling that block. 0:25

So, it jumps from here, in this hide method, 0:30

down to monster.hide, right here, and executes this block of code. 0:34

Something that's kind of neat that we can do is yield arguments to the block. 0:42

Now we know that from earlier lessons that we can provide arguments to the block. 0:48

So, we'll just say if a block is given here, 0:54

let's provide this argument and what argument would that be? 0:59

Well, if wanted to we could provide the actions variable and 1:04

then we would have access to that in the block, but 1:08

let's do something a little more interesting and yield self. 1:12

self is the instance of the monster. 1:18

So we'll get the monster instance inside of the block. 1:23

Which means, 1:26

we could put this in as an argument called monster. 1:33

And in here, we would have access to the monster variable. 1:38

And actually, let's just put that in as m. 1:43

And let's print out the actions here, just to see what it looks like. 1:47

Printed out the scoreboard. 1:58

Let's go back up. 1:59

And this is pretty neat right here, screams, scares, runs, and hides. 2:01

And let's go ahead and just prove that we can get access to all the methods in here. 2:07

We define an inspect method. 2:13

We'll just say inspect is the name and the actions. 2:19

Clear my screen. 2:32

Run this one more time. 2:33

And here we go, 2:36

we've implemented an inspect method that we call from inside of this block. 2:37

This is not something you totally need to do, but it is pretty cool and 2:43

something that you will see in Ruby programs. 2:46

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Ruby Blocks

Build a Monster Class: Part 4

Code Samples