As each Enumerable method is explained, we'll use a common set of examples:
- a simple array of numbers
- a PetInventory class, which manages a collection of Pet objects
- a file that contains a list of "pokey things"
- a LogData class which iterates through Heroku log files in a RAM-friendly way
Array of Numbers
Most examples will start with the simplest Enumerable class: an array called numbers. This is what the value will be:
@numbers = [1, 0, 3, 2, 5, 4, 7, 6, 9, 8]
We've created a class called PetInventory to demonstrate how any class that maintains a collection of items can use the Enumerable module as a mixin. PetInventory manages inventory for a pet store.
As is common with collection classes, we've also defined a class for the items that will be collected; in this case, Pet objects. Each Pet object in the collection tracks how many of that type of pet the store has in stock, and how many legs that pet has. We could track all sorts of info, but for our examples we'll limit ourselves to just those couple pieces of information.
@inventory = PetInventory.new
Here's our initial pet inventory:
|pet||legs||# in stock|
All of our examples will start out with this list of pets.
Ruby's File class uses Enumerable as well. Included in the examples is a file of "pokey things":
@pokey_things = File.open('./data/pokey_things.txt', 'r')
The file itself has the following content:
cactus poles knife cactus holding poles with knives attached
Heroku Log Data
The PetInventory class isn't very useful in real life, so we created the start of a class that can be used to manage Heroku log files. It uses the Enumerable module so that it doesn't have to hold the contents of the entire log file (which could be enormous) into memory.
@requests = LogData.new('./data/heroku.log')
The log file itself has a couple dozen records. You can view it here: