CLI Assessment Prep 👨🏻‍💻 👩🏻‍💻

Possible Assessment Questions

1. What is a gem? A packaged Ruby application or library

2. What is a shebang line? What does it do? It is telling us where to find the library we are going to use to run this code

3. What does require_relative do? Use require_relative when you are referring to a file that is relative to the current file you are working on (basically, within the same project directory)

4. Explain your executable file

5. Explain module, name-spacing, difference between class methods and instance methods?

Example: EcommerceApp::CLI.new.start

EcommerceApp(a module): We need this to distinguish our CLI class from other modules if we have any

CLI(a class)

.new(initialize): a class method, how do you tell? look at the receiver, which is the left to the dot "CLI.new"

.start: an instance method

::double colon, name-spacing, nested within the module of EcommerceApp

Class method VS Instance method short read

• A method provides functionality to an Object
• Class method calls on the class, provides functionality to the CLASS itself
• Instance method calls on the instance OF the class, provides functionality to ONE instance of the class

6. "self is implicit" meaning?

• Every method you call is received by some object, the object receiving the method call is the receiver.
• If you mention the object in the call, that's "explicit", if you call a method in the same object as the context without mentioning "self", that's "implicit".

7. Truthy VS Falsey
In Ruby only false and nil are falsey. Everything else is truthy (yes, even 0 is truthy).

Ruby Essentials (From the checklist given)

1. Basic control flow - how "if" statements work
Essentially check whether a condition is true or not

2. Variable scopes - method, instance and class
Scope refers to what variables are available at that time. More info: Ruby Scopes

• Instance Variables: Sharing data inside a Ruby object
  
• Local Variables: The narrowest scope, defined inside the methods
  

3. Object instantiation - #new (and possibly #initialize)

• We create a new instance of a class by calling the method new on that class, we also say that we “instantiate” that object
• By calling Person.new we instantiate a new person object.

4. The meaning of the "self" keyword
"Self" points to the object that "owns" the currently executing code

5. Method types - class vs. instance methods (look above)

6. Method return types - knowing what methods return
The Differences Between Puts, Print & P

• Puts: Every message has its own line
• Print: Print without a newline
• P: shows a more “raw” version of an object
• Return: Return values

7. Iterating through collections - at least using #each with a block

Extras

• Single Responsibility Principle
  • API Class - bring in external API here, instantiate my objects
  • Object Class (Listing/Category) - where objects are created and stored for user display
  • CLI Class (Command Line Interface) - the controller of my app, communicates with my user, handle user input/output
• Separation of Concerns
• DRY code (Don't repeat yourself)
• Remember Object-Oriented: In Ruby, everything is an object.