Switch. A SwitchCase Simulation

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#1

the greatest things get invented during boredom

Switch - Switch Case Statement Simulation in Lua

A small module for creating a switch case simulation with Builder syntax.
This attempts to mirror the behaviour of switch case statements in Visual Basic.

Module Link: Switch Module - Roblox

Documentation

Switch Module

local Switch = require(Switch)

Returns a function which can be used for constructing switch case objects (see example)

Switch Case Object

Metamethods
__call (when it is called like a function) - Runs the switch case statement
Example:

SwitchCase(n) --n is the variable to be checked against the condition

Properties:
dictionary _callbacks - A storage table used for holding the callbacks
function _default - The default function for undefined conditions

Methods:
SwitchCaseObject case(value, callback) - binds a callback to specified value.

WARNING: This function has only been tested on strings and numbers, it may behave weirdly with other datatypes

SwitchCaseObject default(callback) - binds the default function to a callback

Example

Below is an example for Switch

local Switch = require(script.Switch) --Load the Switch module

local newConditional = Switch() --Create a new SwitchCase using builder syntax
  :case("Player1", function() --Setup a case value callback
    print("Player 1 is outstanding")
  end)

  :case("Player2", function()
    print("Player 2 is amazing")
  end)

  :default(function() --allows you to manage undefined conditions. SwitchCase will error if this is not declared and you use an invalid value
    print("not declared")
  end)

local Player1Name = "Player1"
local Player2Name = "Player2"
local unwantedValue = false

newConditional(Player1Name) --> Player 1 is outstanding
newConditional(Player2Name) --> Player 2 is amazing
newConditional(unwantedValue) --> not declared
Issues

Make sure to leave issues below if you find any.

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#2

Nice module, I’ve created one like this before and it’s super helpful.

Would you be able to use a pastebin paste to show the source to those who cannot view it currently?

3 Likes
#3

Source Code is now available here

1 Like
#4

Switch cases usually has a break statement, how is this use case supported?

#5

Weird enough I just learnt what these were today and all of a sudden this pops up. Great work I’ll be sure to use it in the future.

#6

Since this uses callbacks instead of it being a statement, break statements dont need to be used, I already knew most other languages with this implementation use break part of it’s statement.

It’s not worth implementing something like this if it’s unnecessary and may affect performance.

1 Like
#7

A really simple, but useful module. Thank you.

2 Likes
#8

I guess you can pretend that end) is break

#9

Edit: annnd I reply to the wrong person again. Sorry about that!

You could pass a controller object through that would indicate to the switch object to skip the remaining cases when invoked. Ex:

--Values passed through 'resolve' would be returned instead of what the actual function may return (similar to how promises work)
Switch()
    :case('Player1', function(resolve)
        --do stuff
        resolve(...)
    end)

I only suggest this up because multi-case operations would be a nice addition that would reduce boilerplate code.

1 Like
#10

How is this better than If and ElseIf Statements (Just a Question)

1 Like
#11

it’s just syntax sugar mostly. some people might prefer that

#12

https://www.google.com/search?q=switch+statement+vs+if+else&rlz=1C1CHBF_enUS902US902&oq=switch+statement+vs+&aqs=chrome.0.0j69i57j0l6.3266j0j7&sourceid=chrome&ie=UTF-8

tl;dr easier to test many expressions

2 Likes
#13

Usually switch statements are better in performance for large amounts of conditionals but its hard to say for this LUA switch statement

1 Like
#14

Yeah, Lua(u) has no switch, so you don’t get the compile-time benefits in Lua(u) that you would get in a language that actually has this.

#16

Not sure if I did something wrong, but creating a new switch case gives you an error making the module unusable:

attempt to call a Instance value.

#17

Can you send your code so that I can debug the issue, just sending the error wont tell me what the issue is.

1 Like
#18

Oh my bad. This is the script:

local a = "2"

local switch = game:GetService("ServerStorage").Extensions.Switch_Case_Simulation

local newConditional = switch() --This errors

:case("2", function()
	print("Correct value!")
end)

:case("1",function()
	
end)

newConditional(a)
#19

You did not require the module. You’ve created a reference to the Roblox object, not the table returned by it

3 Likes
#20

Oh that’s a stupid mistake, I always forget to add ‘require’ on modules :sweat_smile:

#21

Sorry for bumping but lets say a thousand of switch cases would be used for whatever reason would it still perform really well?