How to remove a lua table entry by its key?

Wookai picture Wookai · Nov 18, 2009 · Viewed 77.5k times · Source

I have a lua table that I use as a hashmap, ie with string keys :

local map = { foo = 1, bar = 2 }

I would like to "pop" an element of this table identified by its key. There is a table.remove() method, but it only takes the index of the element to remove (ie a number) and not a generic key. I would like to be able to do table.remove(map, 'foo') and here is how I implemented it :

function table.removekey(table, key)
    local element = table[key]
    table[key] = nil
    return element
end

Is there a better way to do that ?

Answer

Amber picture Amber · Nov 18, 2009

No, setting the key's value to nil is the accepted way of removing an item in the hashmap portion of a table. What you're doing is standard. However, I'd recommend not overriding table.remove() - for the array portion of a table, the default table.remove() functionality includes renumbering the indices, which your override would not do. If you do want to add your function to the table function set, then I'd probably name it something like table.removekey() or some such.