function class( t )
  t = t or {}
  t.index = t
  t.new = new
  t.copy = copy
  return t
end

function new( obj, init )
  init = init or {}
  return metatable( init, obj.index )
end

function copy( obj, init )
  local newobj = obj:new(init)
  for n,v in obj do newobj[n] = v end
  return newobj
end

function typeof( x )
  local tx = type(x)
  return tx=='table' and metatable(x) or tx
end

------------------------------------------------------------------------------

local indented, dumpvisited

local indented
function indented( level, ... )
  write( strrep('  ',level), concat(arg), '\n' )
end

local dumpval
function dumpval( level, name, value )
  local index
  if type(name,'number') then
    index = format('[%d] = ',name)
  elseif type(name,'string') and strfind(name,'^[_%a][_%w]*$') then
    index = name ..' = '
  else
    index = format('[%q] = ',tostring(name))
  end
  if type(value,'table') then
    if dumpvisited[value] then
      indented( level, index, format('ref%q;',dumpvisited[value]) )
    else
      dumpvisited[value] = tostring(value)
      indented( level, index, '{  -- ', dumpvisited[value] )
      for n,v in value do
        dumpval( level+1, n, v )
      end
      indented( level, '};' )
    end
  else
    if type(value,'string') then
      if strlen(value) > 40 then
        indented( level, index, '[[', value, ']];' )
      else
        indented( level, index, format('%q',value), ';' )
      end
    else
      indented( level, index, tostring(value), ';' )
    end
  end
end

function dump( name, value )
  dumpvisited = {}
  dumpval( 0, name, value )
end

-- t = { 1,2,3 ; one= 1, two = 'fish', three= 'me', ['4cow'] = 'it' }
-- dump( 't', t )

------------------------------------------------------------------------------

stop = _ERRORMESSAGE

local  alert, traceinfo, gi, gl, dl
    = _ALERT

function gi( i )
  return function() i=i+1 return getinfo(i),i end
end

function gl( level, j )
  return function() j=j+1 return getlocal( level, j ) end
end

function _ALERT(x)
  alert(x)
  traceinfo = {}
  for ar,i in gi(3) do
    tinsert( traceinfo, ar )
    local names  = {}
    local values = {}
    for n,v in gl(i,0) do tinsert( names, n ) tinsert( values, v ) end
    if getn(names) > 0 then
      ar.lnames  = names
      ar.lvalues = values
    end
  end
  debug()
end

function dl( level )
  local i, ar  = 0, traceinfo[ level or 1 ] or {}
  local names  = ar.lnames or {}
  local values = ar.lvalues or {}
  return function() i=i+1 return names[i], values[i] end
end

function locals( level )
  for n,v in dl( level ) do dump( n, v ) end
end

function info() dump( 'traceinfo', traceinfo ) end

-- function fun(x,y) local z=x+y stop"now" end
-- function run(t) for i=1,2 do fun(i,9) end end