Unit Conversion

intervals={

  {"seconds",1}, --the "1" should never really get used but

  {"minutes",60},

  {"hours",60},

  {"days",24},

}



positions={}

for i=1,4 do

  positions[intervals[i][1]]=i

end



function convert_to(value, sourceunits, targetunits)



  local sourcei, targeti = positions[sourceunits], positions[targetunits]

  assert(sourcei and targeti)



  if sourcei<targeti then



    local base=1

    for i=sourcei+1,targeti do

      base=base*intervals[i][2]

    end



    return value/base



  elseif sourcei>targeti then



    local base=1

    for i=targeti+1,sourcei do

      base=base*intervals[i][2]

    end



    return value*base



  else return value end

end



print(convert_to(86400,"seconds","days"))

print(convert_to(1,"days","seconds"))