lua-immutable/README.md

# ImmuTable

This is a native Lua library that allows the creation of immutable tables.

## Build

Lua 5.1/5.2/5.3+ or LuaJIT 2.0+ built from source code is a prerequisite. Lua can be downloaded from the [lua.org downloads page](https://www.lua.org/ftp/), and LuaJIT can be downloaded from the [LuaJIT.org downloads page](http://luajit.org/download.html).

`make LUA=/path/to/lua_dir`
or for LuaJIT: `make LUA=/path/to/luajit_dir LUASUFFIX=jit`

## Usage

```
local immutable = require "immutable"
local Vec2 = immutable({"x","y"}, {
    len2=function(self)
        return self.x*self.x + self.y*self.y
    end,
    is_a_vec2 = true,
    __add=function(self, other)
        local cls = getmetatable(self)
        return cls(self.x+other.x, self.y+other.y)
    end,
    __tostring=function(self)
        return "Vec2("..tostring(self.x)..", "..tostring(self.y)..")"
    end,
})
local v = Vec2(2, 3)
assert(v.x == 2 and v.y == 3)
local v2 = v + Vec2(0, 1)
assert(v2 == Vec2(2, 4))
local t = {[v2]='yep'}
assert(t[Vec2(2,4)] == 'yep')
assert(Vec2(2,0):len2() == 4)
assert(Vec2(2,0).is_a_vec2)
```