-- Functions are first class variables

-- Using OO principles in Lua
-- See http://www.wellho.net/course/ubfull.html

--[[
This is an example which sets up a number of
composite pieces of information (about people)
each in a table, and associates various pieces
of logic with each of them according to their
role in the organisation.

The tables are then made members of an overarching
table allowing the whole data to be handled as a
single entity.

A loop through the overall table the allows Lus to
run the appropriate code for each person without
the need for condition branches in the source -
the selection of the correct logic is automatic,
and additional types of person can be added in
without the need for code changes here too!
]]

function oik()
        print ("does the real work!")
        end

function manager(what)
        print ("health and safety check")
        what()
        print ("laze around and moan")
        return "results"
        end

function director(what)
        print ("makes policy")
        what()
        print ("gets sloshed in pub and moans")
        return "prophet"
        end

action = oik
action()

stafflevels = {manager, director}
for i,current in ipairs(stafflevels) do
        current(action)
        end

print ("==========================")

-- Polymorphic tables!
----------------------

thom = {approach = manager, name = "Thomas",
        age = 21}
damien = {approach = manager, name = "Damien",
        age = 26}
graham = {approach = director, name = "Graham",
        age = 54}

-- A table of objects

team = {["Frisbee Captain"] = thom,
        God = damien,
        ["Beard Ownership"] = graham}

-- Through which we can iterate

-- next is great with ginormous tables
-- as it steps though with little extra memory

quay,bollard = next(team, nil)
-- "tato" = "team age total"
tato = 0 ; tsize = 0;
while quay do
        print (quay,bollard["name"],
                bollard["approach"](oik),
                bollard["age"],"\n")
        tato = bollard["age"] + tato
        tsize = tsize +1;
        quay,bollard = next(team, quay)
        end

print (string.format("Average age %.2f",
                tato/tsize))

--[[

[trainee@easterton al]$ lua fav
does the real work!
health and safety check
does the real work!
laze around and moan
makes policy
does the real work!
gets sloshed in pub and moans
==========================
makes policy
does the real work!
gets sloshed in pub and moans
Beard Ownership Graham prophet 54

health and safety check
does the real work!
laze around and moan
Frisbee Captain Thomas results 21

health and safety check
does the real work!
laze around and moan
God Damien results 26

Average age 33.67
[trainee@easterton al]$

]]