lua: user input to reference table

Question

I am having trouble with my tables, I am making a text adventure in lua

local locxy = {}
      locxy[1] = {}
      locxy[1][1] = {}
      locxy[1][1]["locdesc"] =  "dungeon cell"
      locxy[1][1]["items"] = {"nothing"}
      locxy[1][1]["monsters"] = {monster1}

The [1][1] refers to x,y coordinates and using a move command I can successfully move into different rooms and receive the description of said room.

Items and monsters are nested tables since multiple items can be held there (each with their own properties).

The problem I am having is getting the items/monsters part to work. I have a separate table such as:

local monsters = {}
    monsters["rat"] = {}
    monsters["rat"]["Name"] = "a rat"
    monsters["rat"]["Health"] = 5
    monsters["rat"]["Attack"] = 1

I am using a table like this to create outlines for various enemy types. The monster1 is a variable I can insert into the location table to call upon one of these outlines, however I don't know how to reference it.

print("You are in ", locxy[x][y]["locdesc"]) -- this works
print("You can see a ", locxy[x][y]["monsters]["Name"],".") - does not work

So I would like to know how I can get that to work, I may need a different approach which is fine since I am learning. But I would also specifically like to know how to / if it possible to use a variable within a table entry that points to data in a separate table.

Thanks for any help that can be offered!

Etan Reisner · Accepted Answer · 2014-10-01 20:15:40Z

1

This line

locxy[x][y]["monsters]["Name"]

says

look in the locxy table for the x field
then look in the y field of that value
look in the "monsters"` field of that value
then look in the "Name" field of that value

The problem is that the table you get back from locxy[x][y]["monsters"] doesn't have a "Name" field. It has some number of entries in numerical indices.

locxy[x][y]["monsters][1]["Name"] will get you the name of the first monster in that table but you will need to loop over the monsters table to get all of them.

Style notes:

Instead of:

tab = {}
tab[1] = {}
tab[1][1] = {}

you can just use:

tab = {
    [1] = {
        {}
    }
}

and instead of:

monsters = {}
monsters["rat"] = {}
monsters["rat"]["Name"] = "foo"

you can just use:

monsters = {
    rat = {
        Name = "foo"
    }
}

Or ["rat"] and ["Name"] if you want to be explicit in your keys.

Similarly instead of monsters["rat"]["Name"] you can use monsters.rat.Name.

answered Oct 1, 2014 at 20:15

Etan Reisner

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1 Comment

mixedfr00tjam Over a year ago

Thanks for the very quick and helpful response.

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