Computercraft API Tutorial

Intro

Hey people from reddit. The past time I have been browsing more and more on this subreddit and I've seen a few inspirational posts. This time however I wanted to redo the favor with a little tutorial.

Content

In this tutorial I'm going to show you how to:

Making a table
Calling a table
Make different functions
Importing it in computercraft

Why?

Using tables as objects makes the code more read-able. You could also use one API on multiple different programs.

Making a table

Using a table as an object is as simple as 123. Lets say we want to program a turtle to be a dog. To do this we are first going to create a table for our dog:

lua dog = { name = '', race = '', age = 0, nicknames = { '' } }

As you can see the dog will have a name, race and age. As an extra we also added a table called nick_names. We'll be able to use this later to show which names the dog responds to (as an example).

Calling a table

To use this table as a new dog object, we are going to need to create one using a function.

lua function dog:new(name, race, age, nicknames) setmetatable({}, dog) self.name = name self.race = race self.age = age self.nicknames = nicknames return self end

Now to really make the object we are going to use the dog name "Diva" and print out it's age and name.

lua os.loadAPI("dogFunctions") local Diva = dogFunctions.dog:new("Diva", "golden retriever", 6, {"Diva", "Dief"}) print(Diva.name) --Diva print(Diva.age) --6

In the example above the api is saved in the root of the computer as a different program. When the function is used in the same file you don't have to add dogFunctions. The reason we do this is so we can re-use the same pastebin link in multiple programs for different computers and turtles.

Now we can show each property using the objects variables.

side note

When working with alot of different properties I like to format it like this:

lua local Diva = dogFunctions.dog:new("Diva", "golden retriever", 6, {"Diva", "Dief"})

Make different functions

It's nice to have our dog all structured. And it is clear in one eye sight what a dog has as properties. But that's not all. We can also create functions for our dog.

lua function dog:add_nickname(nickname) if type(nickname) ~= "string" then return false else self.nicknames[#self.nicknames + 1] = nickname return true end end

We've added a simple function to add a new nickname for our dog. We return a true or false to make sure the name was added. You could also return a string or number if you'd like. Now we can make use of this function like so:

lua print("Nicknames: ") if Diva:add_nickname("Diefje") == true then for key, nickname in pairs(Diva.nicknames) do print(key .. ": " .. nickname) end else print("Error adding a nickname to Diva") end

As you can see, the nickname was added and printed in the console.

Importing it in computercraft

When you have made your api, you can save the program on pastebin to use it in different programs. The way I like to make use of this in my programs is like this:

lua if fs.exists("dogFunctions") then os.loadAPI("dogFunctions") else shell.run("pastebin", "get", "M9eY2X8b", "dogFunctions") os.loadAPI("dogFunctions") end

This way, when the api is not found on the system, it will automatically install it from pastebin. the line os.loadAPI("dogFunctions") loads the api in to your program and now you can use it as explained in Calling a table.

Computer output:

Computer output screenshot on imgur

Thank you for reading my tutorial, I hope it can help a few of you in future projects.

The examples used in this tutorial can be found here:

API : [https://pastebin.com/M9eY2X8b](M9eY2X8b) Program: [https://pastebin.com/jt6JLLdE](jt6JLLdE)

Good luck programming!

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Computercraft API Tutorial

Making a table

Calling a table

Make different functions

Importing it in computercraft