Lua class with safe sentinel

class.lua

--[==[

(c) 2020 MIT licensed

Usage example:

local class = require("class")
-- local class = require("class").safe() -- add .safe() on require to make class safe (Lua pcall is wrapped in each class function)

local my_class = class.new(start_param_1, start_param_2 --[[, ...]])
-- local my_class = class(--[[, ...]]) -- .new is optional

my_class:my_method(param_1, param_2, --[[, ...]])

print(my_class.my_value)

--]==]

local unpack =  table.unpack or unpack
local remove = table.remove
local _fail = fail -- luacheck: ignore

local class = {}
class.__index = class

-- STATIC METHODS

class.safe = function()
  for key, value in pairs(class) do
    if type(value) == "function" then
      class[key] = function(...)
        local result = {pcall(value, ...)}
        if remove(result, 1) then
          return unpack(result)
        else
          return _fail, unpack(result)
        end
      end
    end
  end
  return class
end

function class.new(start_param_sample)
  local self = setmetatable({}, class)
  
  self.value_sample = start_param_sample
  
  return self
end

setmetatable(class, {
  __call = function(self, ...)
    return self.new(...)
  end
})

-- METHODS

function class:method_sample(param_sample)
  self.value_sample = assert(param_sample)
end

return class