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Compact Conditional Statements?

Asked Apr 20, 2014409 views2 answers

Hello. I'm asking this question because I want to learn the basis of compacted conditionals (e.g. m or 17).

I've been scripting for quite a while, I'm certainly not new at it, but somehow this slipped me by, and I feel like it could give me a chance to write more efficient code.

I've read up on it, and the syntax confuses me, and I've been on Scripting Helpers for a while only answering questions, so I figured I'd ask here.

Anyway, my question is, what is the syntax of a conditional that is simply put; an example-

a or b

c or d

m not 666

... and when exactly would be the most efficient time/place in code to do it?

Thanks for reading; all replies are appreciated!

AnonymousApr 20, 2014

2 answers

✓ Accepted answer

It's useful when you want to do a little logic statement, but don't feel like having an additional scope for that. The syntax is simply like that, just like you wrote. So here is a little example:

local a = false
local b = 123

c = a or b -- 'c' would end up as 123, because 'a' is false, so it'd check b

m = c or d -- same as before

d = m ~= 666 or m -- 'd' would be 123, because it wasn't equal to 666 so I choose for it to be the old value instead

AnonymousApr 20, 2014Edited Apr 20, 2014Permalink

Have you read my blog post? https://scriptinghelpers.org/blog/two-scripting-tips-which-will-make-scripting-easier

I normally use those to script if-then blocks. What's really handy to note is that Lua handles everything as true except false and nil. You can use this!

function get(tab, provided)
local to_index = provided or 1 -- if provided is not available, return 1
return tab[to_index]
end

Also, the syntax you use is incorrect. You should try to think of "or", "and" and "not" as functions.

I will rewrite those without using and/or/not:

function OR(arg1, arg2) -- equivalent of arg1 or arg2
if arg1 == nil then 
	return arg2
elseif arg1 == false then
	return arg2
end
return arg1
end

function AND(arg1, arg2) equivalent of arg1 and arg2
if arg1 == nil then 
	return arg1
elseif arg1 == false then
	return arg1
end
return arg2
end

function NOT(arg1) -- equivalent of arg1
if arg1 == nil then
return true
elseif arg1 == false then
return true
end
return false
end

There are two differences with these functions though. These statements only evaluate when necessary. For example, torso = Player.Character and Player.Character:FindFirstChild("Torso") only calls :FindFirstChild if Player.Character is not nil or false. In that case, this statement never errors (well, unless Player is not a table/instance or Player is a table and the Character field is present and Player.Character does not have a function called FindFirstChild - but those errors are not likely to happen).

The other difference is that you can just call a function: 'a()' is a valid statement if a is a function. a or b is not a valid statement though, you need to do something with it:

a = a or b z = d and c b = not r

Those statements are valid.

AnonymousApr 20, 2014Permalink

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