Development Glossary

application - A piece of software, written in one or more programming languages. Firefox, Angry Birds, and Wordpress are all applications.

argument - Methods take arguments, also called "parameters". Arguments allow you to pass data into a method.

array - A data structure that holds multiple items. Sometimes called a list.

chain - Methods are chained together when you take the output of one and send it on to the other. For example my_array.sort.reverse would take an array, sort it, and then reverse the sorted array.

character - A letter or symbol in a string. The string "ruby!" has five characters: r, u, b, y, and an exclamation point.

class - In object-oriented programming, everything has a class. Each class has various data structures and methods associated with it. For example, in Ruby there is an Array class, and all arrays have a join method, a sort method, and so on.

compile - Some programming languages are "compiled". That means in order to use an application written in that language, you have to compile the source code into an code that the computer can run. C, C#, and Java are compiled. The alternative is interpreted languages.

conditional - A control structure that runs some code only when certain conditions are met. The code: puts "long name!" if name.length > 5 will only print "long name!" if the name is longer than 5 letters.

data structure - A piece of code that lets you store a certain kind of information. Common data structures are hashes, arrays, and sets. Each data structure lets you store different information. An array is just a list of things, a hash is a list of things with labels, and a set is a list of things with no duplicates.

evaluate - Run code. A piece of code is said to evaluate to some result. If we have an array of four items, the code array.length evaluates to 4.

hash - In Ruby, a hash is an array with labels known as "keys". The hash {:name => "Sarah", :company => "Google"} has two values, "Sarah" and "Google" with two keys, :name and :company. In Ruby, keys and values can by objects of any type, but keys are usually either strings or symbols. Sometimes called a dictionary or an associative array.

instance - When you want to create an object, in instantiate a class, creating an instance. The class is the theoretical category, but each individual thing is called an instance. For example, your specific cats kali and artemis are instances of the Cat class.

interpret - Some programming languages are "interpreted". When you want to use an application written in these languages, an interpreter looks at the code and runs it while you're using it. Popular interpreted languages are Ruby, Javascript, Python, Perl, and Lua. The alternative is compiled languages.

IRB - The Interactive Ruby Shell lets you type Ruby code and see what it does.

method - A snippet of code that does something. In Ruby you define a method with the def command. You can then call the function by name. Methods can sometimes have parameters, or arguments, which are pieces of data that you pass to the function to do something with.

operator - Something in a programming language that lets you

parameter - See argument.

print - Displaying something in the terminal, or on a web page.

programming language - A language that a computer can understand. You type code in a given language into the computer and then interpret or compile it. There are thousands of programming languages, but some other common ones are PHP, Java, C, C#, and Python.

Ruby - A programming language commonly used for web applications.

run - Can can be "run", which for Ruby means having an interpreter go through the code step by step and do what the code says. You can do this with the ruby command in the terminal, or by starting a Rails server and letting Rails run your code.

string - A data structure used to store a list of characters. Like a string of lights it's a bunch of little pieces tied together. Usually strings are wrapped in quotes: "hello world!" is a common string.

symbol - Symbols are labels that are used for various purposes in Ruby, most commonly as keys in hashes. They're nice to use as labels because they're immutable (they never change).

terminal - A program that lets you type commands directly into your computer. Sometimes called a command prompt.

value - Typically when people refer to a value, they mean a specific piece of data. 4 is a value, "hello world!" is a value. Hashes also have values (see hash).

variable - A name with a values assigned to it.

web application - An application which runs on the internet so people can access it through a web browser.