LUA: Looking for a specific table by its variable

Question

I'm currently starting work on a text adventure game in Lua--no addons, just pure Lua for my first project. In essence, here is my problem; I'm trying to find out how I can do a "reverse lookup" of a table using one of its variables. Here's an example of what I've tried to do:

print("What are you trying to take?")
bag = {}
gold = {name="Gold",ap=3}
x = io.read("*l")
if x == "Gold" then
     table.insert(bag,gold)
     print("You took the " .. gold.name .. ".")
end

Obviously, writing a line like this with every single object in the game would be very... exhausting--especially since I think I'll be able to use this solution for not just taking items but movement from room to room using a reverse lookup with each room's (x,y) coordinates. Anyone have any ideas on how to make a more flexible system that can find a table by the player typing in one of its variables? Thanks in advance!

-blockchainporter

Answer 1

This doesn't directly answer your question as you asked it, but I think it would serve the purpose of what you are trying to do. I create a table called 'loot' which can hold many objects, and the player can place any of these in their 'bag' by typing the name.

bag = {}
loot = {
    {name="Gold", qty=3},
    {name="Axe", qty=1},
}

print("What are you trying to take?")
x = io.read("*l")
i = 1
while loot[i] do
    if (x == loot[i].name) then
        table.insert(bag, table.remove(loot,i))
    else
        i = i + 1
    end
end

For bonus points, you could check 'bag' to see if the player has some of that item already and then just update the quantity...

while loot[i] do
    if (x == loot[i].name) then
        j, found = 1, nil
        while bag[j] do
            if (x == bag[j].name) then
                found = true
                bag[j].qty = bag[j].qty + loot[i].qty
                table.remove(loot,i)
            end
            j = j + 1
        end
        if (not found) then
            table.insert(bag, table.remove(loot,i))
        end
    else
        i = i + 1
    end
end

Again, this isn't a 'reverse lookup' solution like you asked for... but I think it is closer to what you are trying to do by letting a user choose to loot something.

My disclaimer is that I don't use IO functions in my own lua usage, so I have to assume that your x = io.read("*l") is correct.

---

PS. If you only ever want objects to have a name and qty, and never any other properties (like condition, enchantment, or whatever) then you could also simplify my solution by using key/val pairs:

bag = {}
loot = { ["Gold"] = 3, ["Axe"] = 1 }

print("What are you trying to take?")
x = io.read("*l")
for name, qty in pairs(loot) do
    if x == name then
        bag.name = (bag.name or 0) + qty
        loot.name = nil
    end
end