Lua questions #2

[LifeDigger (Life)]

Hello!

@StarJ3M

What does pcall() do, and why is it used in datastores, when should I use it?

Pcall functions basically catches if any errors happen in the function. The reason why they should be used inside of things when using data stores is because the API that datastores use can sometimes go down which can cause errors in your script causing the whole code to stop working as it should.

If you ever see this message in the docs (old ones) then you should use a pcall function:

In the new docs it looks like something like this:

@StarJ3M

How does the Datastore Service Work?

What do you mean by “How does the Datastore Service Work?”. What part do you need to understand? In general you just get the datastore service and then get the data store from the service and then once you have the data store do things like getAsync and as such.

@StarJ3M

What is a tuple?

Inside of Lua a tuple is a list of variables. Often you will find them inside of things such as a method accepting multiple variables/arguments.

You can get a bit more info here: https://developer.roblox.com/en-us/articles/Tuple#:~:text=In%20Roblox%2C%20the%20tuple%20type,means%20it%20returns%20multiple%20values.

@StarJ3M

Whats the difference from Arguments and Parameters?

To be honest I am not really sure how to explain what they are but here is an image I found on google which shows it well (language in the image is not lua but you get the idea).

@StarJ3M

What is invoking in luau

Invoking (or at least what I know it off) is normally where you are expecting something back. An example of invoking in a remote function where you invoke the server or client and it expects back a value.

@StarJ3M

What does setfenv do, when should I use it?

Now I have to admit I was not 100% sure about what setfenv and getfenv does. After some quick research it seems to allow you to set a script global variables (also known as environmental/env variables). After doing some research I kinda understand a bit (I kinda get it from using .env in node.js for Discord bots and websites) but still don’t massively understand the use of it (even in the post I will link below which explains it very well said you are very unlikely to ever use it).

What does ``getfenv()`` do?

As others have said, getfenv() returns the environment of your script (“env” for short). But what is an env? You probably know that each script has a script variable by default. It’s a global variable (the one created without using local, i.e. foo = "bar"). But global variables have to be stored somewhere, right? The answer is yes - they are stored within a dictionary table assigned to each script when it runs. That table is called the script’s env. So if that table stores your global variabl…

@StarJ3M

What is type, how does it work, when should I use it?

Basically allow you to get the datatype of a Roblox datatype.

@StarJ3M

What does xpcall do, whats the difference from pcall and when should it be used?

I highly recommend checking this post. It explains xpcalls, pcalls and ypcalls very well.

Pcall(), xpcall() and ypcall() Tutorial - How do they work?

Welcome curious Developers! In this tutorial, I’ll be explaining how pcall() and xpcall() functions work and what happened to ypcall(). Let’s start pcall() pcall() is short for P rotected Call , if the code inside of this function has an error it will yield until the attached function run without any issues and won’t stop the rest of the script. It also returns two values: A bool one and a variant one. local boolValue, variantValue = pcall(function() -- 1 -- this code is protected end) …

@StarJ3M

What is _VERSION When should I use it?

All it does is gives you the current version of Lua. It’s really not at all important for game devs and see 0 uses of it tbh.