I do stuff and forget how. I made this to capture some of it.

Hash table

What is a hash? A hash is used across technologies and domains. As a result the word has a few meanings. To give a simple definition, as it relates to a hash table, a hash is a value (usually a number) you get back from a hash function that represents what was hashed. The thing could be an object or a primitive type. So you call a hash function, you get a value back, simple right?


What is Memoization? Memoization is a programming technique used to speed up calculations and prevent a program from reworking the same sub-problems repeatedly. It’s like caching. When memoizing, you store the results of past operations in a structure where they can be retrieved very quickly. For example, if you were to implement some code to find numbers in the Fibonacci sequence recursively then your function will likely do the same math over and over until it finds the Fibonacci number you specified.


‘GlookupProductFromAttributeSet’ What is this? This is an error I got while working on linking an Alexa device through an A4B (Alexa For Business) device-maker service I was implementing for a project. The sample device-maker service published by Amazon can be found here. I was trying to use the ‘/device/register’ endpoint in the sample service. I generated a code using a curl command to the ‘https://api.amazon.com/auth/O2/create/codepair’ endpoint. Once I’d posted my code and DSN in the body of a request to the ‘/device/register’ endpoint’, I received the following error back from Amazon’s API:

The Linux File System

What is Linux? Linux is the thing that in some form or another all modern computing is built on. It’s a developers best friend. Linux is an operating system that runs almost everywhere. Servers, PC’s, cell phones, etc… It’s usually free too. What is a “file system”? A file system is the part of an operating system that decides where stuff goes. It provides the processes for storing and receiving data.


What is Polymorphism? Inheritance goes hand-in-hand with Polymorphism (an important concept in object-oriented programming wherein objects function interchangeably). In Polymorphism a class inherits from a parent class and gains the ability to function as its parent in places where the parent class would have been required. Due to this type interchangeability, your code becomes more fluid because it allows you to write general logic to handle multiple classes/types instead of specific logic for each.


What is inheritance? Inheritance is a feature of object-oriented programming languages that allows objects to be based upon or derived from other objects. Essentially, you can make new classes from pre-existing classes. For example, if you had an “Animal” class that has a “breathe()” method and you wanted to create a “Dog” class, you wouldn’t want to write a breathe method for your dog class. You already did that in the animal class and the dog is definitely going to need to breathe.