How do you write this shorter? - if-statement

Question

I thought there was and better nice way to write this but I can't remember.
Is there an nicer way to write this in Lua?
if curSwitch == "shapes" then
curSwitch = "colors"
elseif curSwitch == "colors" then
curSwitch = "shapes"
end

Answer 1

Works only if possible 2 values:
curSwitch = (curSwitch =="shapes") and "colors" or "shapes"

Answer 2

How about this.
Start with
oldSwitch = "colors"
curSwitch = "shapes"
Then flip the switch with
curSwitch, oldSwitch = oldSwitch, curSwitch

Answer 3

Note, I don't know Lua.
Usually, for a trigger, you use XOR operation.
Like, whatever B has (0 or 1), when you calculate1 XOR B it will invert the B.
1 XOR 1 = 0; 1 XOR 0 = 1.
You probably can create a map with integer (ideally, a bit) and string and put there {0:"shapes"; 1:"colors"} and then work with the number.
Or, you could just use a true/false for the curSwitch, then it'll look like this (ternary op):
curSwitch ? "shapes" : "colors"
But that's not that fancy if you repeat that everywhere.
Good luck! :)

Answer 4

You can implement such a simple switch using a table.
switch = { shapes = "colors", colors = "shapes" }
curSwitch = "colors"
curSwitch = switch[curSwitch]
print(curSwitch) -- "shapes"
The problem is that if the value does not exist in the table you simply get nil.
curSwitch = "garbage"
curSwitch = switch[curSwitch]
print(curSwitch) -- nil
This can be remedied by an overloaded __index metamethod which triggers an error in the case of absent keys.
m = {
__index = function(t,k)
local v = rawget(t,k) or error("No such switch!")
return v
end
}
setmetatable(switch, m)
curSwitch = "garbage"
curSwitch = switch[curSwitch]
print(curSwitch) -- error!