understanding_classes_and_objects.txt

1. You can get stuff out of a hash by calling the hash, with the key in square brackets []:

---
puts hash_name['key']
---

2. You can get stuff out of a module by requiring the module, then calling it and the function you want to use with a .

---
require "./module_name.rb"

module_name.function()
---

3. You can access variables in a similar way, but using :: instead of .

---
require "./module_name.rb"

module_name::variable
---

So the key idea here is the same, you are using some code to hold things, and you can pull things out of it in a similar way, with [ ], . or ::, The tutuorial says this is takign a key=value style container, then getting something out of it by using the key's name.

---
hash['key']

module.function

module::variable
---

Classes work the same as modules, but there is a lot more complicated stuff going on.

Modules can only be used once, whereas classes can be used many, many times. In ex40.rb, you have an "instance variable" called tangerine and a function called apple.

To use a class, you have to do something similar to "require" for modules. This is called instatiate, which really just means 'create'. You would do this y calling the class's 'new' function.

--
thing = MyStuff.new()
thing.apple()
puts thing.tangerine
---

When you run something like the above, Ruby will craft an empty object with all the functions defined in the original class (make a copy of the empty class). @ means this object, $ means global. SO the @tangerine in the code refers to "the variable in this object called tangerine". Finally, we'll assign this object to a variable so we can use it, and call it later in the code if needed.

Doing the above gives you a copy of the class to use as a blueprint for your new code. When you do a similar thign with the module, you are using that module, of which there is only one.

We have elarned three ways o get things from other, bigger things.

hash/dict style
mystuff['apples']

module style

My_stuff.apples()
puts Mystuff::TANGERINE

class style

thing = MyStuff.new()
thing.apples()
puts thing.tangerines