Return function with multiple returns

[circonian]

Is it possible to return all of the return values from a "different" function that has multiple returns in a single return statement?

Like:

local function somefunc(_iBagId, _iSlotId,)
  -- This might seem pointless, but I wanted an example people would be familiar with --
   return GetItemInfo(_iBagId, _iSlotId)
end

and then call that function and capture everything like:

local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = somefunc(bagId, slotId)

or do you have to capture all of the returns and then return them like:

local function somefunc(_iBagId, _iSlotId,)
   local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = GetItemInfo(_iBagId, _iSlotId)
   return sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality
end

I tried googling for the answer, but no luck.

[Garkin]

Yes, it works. If you call function in return statement, as a result you will get all return values from the called function.

Good example could be unpack() function. It is often called in return statement if you want to return values stored in array (table).

myTable = { "He", "ll", "o ", "Wo", "rl", "d!"}
 
function foo()
    return unpack(myTable)
end

[circonian]

Oh, I had a type-o no wonder I couldn't get it to work.

Thanks

[circonian]

Or maybe it wasn't a type-o.
Does it still work if you do something like:

return _lItemLink and GetMyLinkItemInfo(_lItemLink) or GetItemInfo(_iBagId, _iSlotId)

Sorry I should have just posted the actual code to begin with.

The idea is to call one function GetMyItemInfo(..) to get an items info whether you pass in a bag,slot or link:

local function GetMyLinkItemInfo(_lItemLink)
    local sIcon, iSellPrice, bMeetsUsageRequirement, iEquipType, iItemStyle = GetItemLinkInfo(_lItemLink)
    local iItemQuality = GetItemLinkQuality(_lItemLink)
-- I know iStack & bLocked are not defined & return nil --
-- I'm ok with that, nothing wrong with doing that right ? --
    return sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality
end
 
local function GetMyItemInfo(_iBagId, _iSlotId, _lItemLink)
-- These two below work
    --return GetMyLinkItemInfo(_lItemLink) 
    --return GetItemInfo(_iBagId, _iSlotId)
-- But this one doesn't
    return _lItemLink and GetMyLinkItemInfo(_lItemLink) or GetItemInfo(_iBagId, _iSlotId)
end

and then calling the following fails:

-- Whether I call it with a bagId, slotId or Link they both fail at the same place --
    local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = GetmyItemInfo(iBagId, iSlotId, nil)
    local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = GetmyItemInfo(nil, nil, lLink)
 
    d("sIcon: "..sIcon)
-- I know iStack can be nil if I pass in a link, thats ok --
    if iStack then d("iStack: "..iStack) else d("iStack: Nil") end
 
--***************************************************--
-- iSellPrice: Fails with "Operator .. not supported for string .. nil" --
    d("iSellPrice: "..iSellPrice)
--***************************************************--
 
 
    d("bMeetsUsageRequirement: "..tostring(bMeetsUsageRequirement))
-- I know bLocked can be nil if I pass in a link, thats ok --
    if bLocked then d("bLocked: "..tostring(bLocked)) else d("bLocked: Nil") end
    d("iEquipType: "..iEquipType)
    d("iItemStyle: "..iItemStyle)
    d("iItemQuality: "..iItemQuality)

[Garkin]

Originally Posted by circonian Or maybe it wasn't a type-o. Does it still work if you do something like: return _lItemLink and GetMyLinkItemInfo(_lItemLink) or GetItemInfo(_iBagId, _iSlotId) ... <snip> ...

It fails because of used logical operators (and, or). Logical operators use just the first return value from the function to check if the expression result is true or false. So the function returns just one of values used for evaluation.

If you want to work with multiple return values in logical expression, you will have to store values to the table and then unpack it:

return unpack(_lItemLink and {GetMyLinkItemInfo(_lItemLink)} or {GetItemInfo(_iBagId, _iSlotId)})

But this is probably better:

if _lItemLink then
    return GetMyLinkItemInfo(_lItemLink)
else
    return GetItemInfo(_iBagId, _iSlotId)
end

or shorter and even better is:

if _lItemLink then
    return GetMyLinkItemInfo(_lItemLink)
end
return GetItemInfo(_iBagId, _iSlotId)

Example:

local function GetMyItemInfo(_iBagId, _iSlotId)
    if type(_iBagId) == "string" then --if the first argument is string, it's itemLink
        return GetMyLinkItemInfo(_iBagId)
    end
    return GetItemInfo(_iBagId, _iSlotId)
end
 
--And then call it:
local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = GetMyItemInfo(iBagId, iSlotId)
local sIcon, iStack, iSellPrice, bMeetsUsageRequirement, bLocked, iEquipType, iItemStyle, iItemQuality = GetMyItemInfo(lLink)

[circonian]

Originally Posted by Garkin It fails because of used logical operators. Logical operators uses just the first return value from the function to check if the value is true or false (false is false or nil, everything else is true).

Oh I think I misunderstood how the short-circuit evaluation works. I thought it would capture all of the returns, but only evaluate the first return to see if it should return ALL of those values.

I tried the unpack (before I posted the question), but I guess I was doing it wrong too. I was trying to unpack each individual function call like:

return _lItemLink and unpack({GetMyLinkItemInfo(_lItemLink)}) or unpack({GetItemInfo(_iBagId, _iSlotId)})

Thanks for your help Garkin.