--[[

This is an extended version of the anim_o1.lua demonstration. We have
added a metatable to our farm animal class, allowing us to provide code
to print out cleanly a farm animal, simply by giving the table name. i.e.
we have changed output such as:
        table: 0x9c445f8
into something that relates to the actual data type in the particular table:
        It's a turkey

We have also provide a function in the metatable to define what "<" means
in relation to farm animals ...

]]

-- basics for a farm animal
farm = {}

-- Internal stuff applied to each farm animal
local farm_actions = {}

function farm.getbreed(current)
        return current.breed
        end
function farm.getweight(current)
        return current.w
        end
function farm.getvalue(current)
        return current.cpk * current.w
        end

function farm_actions.__tostring(current)
        return "It's a " .. current.breed
        end

farm_actions.__lt = function (this,that)
        if this:getvalue() > that:getvalue() then
                print (this:getvalue())
                print (that:getvalue())
                return true
        end
        return false
        end

function farm.new(breed,weight,perkilo)
        local now = {}
        setmetatable(now,farm_actions)
        now.w = weight
        now.breed = breed
        now.cpk = perkilo
        now.getbreed = farm.getbreed
        now.getweight = farm.getweight
        now.getvalue = farm.getvalue
        return now
        end

pet = {}
function pet.getvalue(current)
        return current.cost
        end
function pet.new(breed,weight,cost)
        local now = {}
        now.w = weight
        now.breed = breed
        now.cost = cost
        now.getbreed = farm.getbreed
        now.getweight = farm.getweight
        now.getvalue = pet.getvalue
        return now
        end

function loadbeasts(source)
        fh,err = io.open(source)
        lno = 0
        zoobase = {}
        while true do
                lyne = fh:read()
                if lyne == nil then break end
                lno = lno + 1
                current = {}
                for f in string.gmatch(lyne,"[^\t\n]+") do
                        current[#current+1] = f
                        end
                if #current == 0 then break end
                if string.match(current[1],"^#") then break end
                if #current ~= 4 then
                        io.write("Error 16 at line "..lno.."\n")
                        break
                        end
                if current[4] == "f" then
                        zoobase[#zoobase+1] = farm.new(current[1],
                                 current[2], current [3])
                elseif current[4] == "p" then
                        zoobase[#zoobase+1] = pet.new(current[1],
                                 current[2], current [3])
                else
                        io.write("Error 17 at line "..lno.."\n")
                        break
                        end
        end
        return zoobase
end

-- Here comes the main program ...

yard = loadbeasts("zoo.txt")

totval_sofar = 0

for _,v in ipairs(yard) do
        a1 = v:getbreed()
        a2 = v:getweight()
        a3 = v:getvalue()
        totval_sofar = totval_sofar + a3
        print (v,a1,a2,a3)
        end
io.write("Total value is "..totval_sofar.."\n")

--[[ ----------- Sample results

[trainee@easterton nats]$ lua !$
lua animals.lua
It's a turkey turkey 7 14
It's a sheep sheep 27 108
table: 0x9c44768 dog 9 5
table: 0x9c44270 hamster 0.1 6
table: 0x9c445f8 rabbit 3 12
table: 0x9c44d50 dog 28 100
Total value is 245
[trainee@easterton nats]$

]]