Clone vs Copy - any libs for that?

[zgrssd]

I ran into the small issues that tables are generally handed to and from function by reference instead of by value. So I need to channel my inner mad scientist and start cloning.

Some search gave me these code for shallow and deep cloning respectively:

function copy (t) -- shallow-copy a table
    if type(t) ~= "table" then return t end
    local meta = getmetatable(t)
    local target = {}
    for k, v in pairs(t) do target[k] = v end
    setmetatable(target, meta)
    return target
end

function clone (t) -- deep-copy a table
    if type(t) ~= "table" then return t end
    local meta = getmetatable(t)
    local target = {}
    for k, v in pairs(t) do
        if type(v) == "table" then
            target[k] = clone(v)
        else
            target[k] = v
        end
    end
    setmetatable(target, meta)
    return target
end

Now I don't understand enough about metatables, tables and lua in general to be certain if that is code right (it looks like it).
And of course it could help to fold both functions into one with a bool switch/int to tell the maximum depth to clone.

Has annybody already written some code for cloning in his library so I don't repeat the same code?

[ingeniousclown]

This already exists as a global function implemented by ZO:

function ZO_DeepTableCopy(source, dest)
    dest = dest or {}
    
    for k, v in pairs(source) do
        if type(v) == "table" then
            dest[k] = ZO_DeepTableCopy(v)
        else
            dest[k] = v
        end
    end
    
    return dest
end

This excludes metatables, however, and at a glance, it looks like it will crash on any circular reference.

[zgrssd]

Originally Posted by ingeniousclown This already exists as a global function implemented by ZO: function ZO_DeepTableCopy(source, dest)     dest = dest or {}         for k, v in pairs(source) do         if type(v) == "table" then             dest[k] = ZO_DeepTableCopy(v)         else             dest[k] = v         end     end         return dest end This excludes metatables, however, and at a glance, it looks like it will crash on any circular reference.

Since I only have data I want to hand out data from my Saved Vars without having any side effects this is ideal.

[Wobin]

I used the following in GuildLib

local visitedTables = {}
 
function LibGuildInfo:DeepTableCopy(source, subCall)
    local dest =  {}
    
    for k, v in pairs(source) do
        if type(v) == "table" and not visitedTables[v] then                     
            visitedTables[v] = true
            dest[k] = self:DeepTableCopy(v, true)            
        else
            dest[k] = v
        end
    end
    
    if not subCall then visitedTables = {} end
 
    return dest
end

It kept a list of table references in the external local, and just copied the reference if it had already been traversed.