Re: LeftJoins with tables (removing values from tables)

[Mark Hamburg <mhamburg@...>]

Why a weak-table for the collections or why not a weak table for the results
of the subtraction? Is this just the "an e-mail editor is not really a code
editor" issue?

Mark

on 9/25/04 10:45 AM, Milano Carvalho at milanogc@hotmail.com wrote:

> You would store the collection's objects as keys of a table.
> The values relative to each key would be used to store whatever you want.
> 
> For example:
> 
> local mt = {__mode = "k"}
> 
> local t1 = setmetatable({}, mt) -- collection t1
> t1[obj1] = true -- insert obj1 into collection t1
> t1[obj2] = true -- insert obj2 into collection t1
> 
> local t2 = setmetatable({}, mt) -- collection t2
> t2[obj2] = true -- insert obj2 into collection t2
> 
> So the subtract function would be for example:
> 
> function subtract(t1, t2)
> local r = {}
> 
> for k, v in pairs(t1) do
> if not t2[k] then
> r[k] = v
> end
> end
> 
> return r
> end
> 
> Milano