lua protected call

func.lua

local function _xpcall(func, params)
  assert((type(params) == 'table'), "input param must be a table")
  
  status, err, ret = xpcall (func, debug.traceback, params)
  assert(status, err)
  assert((type(err) == 'table'), "return value must be a table")
  
  return err
end

-- ERROR EXAMPLE


function f (...)
  local arg=...

  local a,b = arg[1], arg[2]
  
  return {a + "b", "jim"}
end

function f2 (...)
  local arg=...

  local a,b = arg[1], arg[2]
  
  return {a + b, "jim"}
end

local t 
t = _xpcall(f2, {1,5})
t = _xpcall(f, {1,5})











function f (...)
  local arg=...

  local a,b = arg[1], arg[2]
  
  return {a + b, "jim"}
end

status, ret, err = xpcall (f, debug.traceback, {1,5})

print ("status", status)
print ("ret", ret)
print ("err", err)

--[[
status	true
ret	table: 0x420650
err	nil
]]--




-- ERROR EXAMPLE


function f (...)
  local arg=...

  local a,b = arg[1], arg[2]
  
  return {a + "b", "jim"}
end

status, ret, err = xpcall (f, debug.traceback, {1,5})

print ("status", status)
print ("ret", ret)
print ("err", err)

--[[
status	false
ret	/Users/jamesfolk/Documents/lua_scratch_pad/main.lua:23: attempt to perform arithmetic on a string value
stack traceback:
	/Users/jamesfolk/Documents/lua_scratch_pad/main.lua:23: in function 'f'
	[C]: in function 'xpcall'
	/Users/jamesfolk/Documents/lua_scratch_pad/main.lua:26: in function </Users/jamesfolk/Documents/lua_scratch_pad/main.lua:1>
	/Users/jamesfolk/Documents/lua_scratch_pad/main.lua:1: in main chunk
err	nil
]]--