Modding Library (modlib)

Multipurpose Minetest Modding Library

About

No dependencies. Licensed under the MIT License. Written by Lars Mueller aka LMD or appguru(eu).

API

Mostly self-documenting code. Mod namespace is modlib or _ml, containing all variables & functions.

Bluon

Binary Lua object notation. Experimental. Handling of subnormal numbers (very small floats) may be broken.

new(def)

def = {
    aux_is_valid = function(object)
        return is_valid
    end,
    aux_len = function(object)
        return length_in_bytes
    end,
    -- read type byte, stream providing :read(count), map of references -> id
    aux_read = function(type, stream, references)
        ... = stream:read(...)
        return object
    end,
    -- object to be written, stream providing :write(text), list of references
    aux_write = function(object, stream, references)
        stream:write(...)
    end
}

:is_valid(object)

Returns whether the given object can be represented by the instance as boolean.

:len(object)

Returns the expected length of the object if serialized by the current instance in bytes.

:write(object, stream)

Writes the object to a stream supporting :write(text). Throws an error if invalid.

:read(stream)

Reads a single bluon object from a stream supporting :read(count). Throws an error if invalid bluon.

Checking whether the stream has been fully consumed by doing assert(not stream:read(1)) is left up to the user.

Format

• nil: nothing ("")
• false: 0
• true: 1
• Numbers:
  • Constants: 0, nan, +inf, -inf
  • Integers: Little endian U8, U16, U32, U64, -U8, -U16, -U32, -U64
  • Floats: Little endian F32, F64
• Strings:
  • Constant: ""
  • Length as unsigned integer: T8, T16, T32, T64
• Tables:
  • List and map part count as unsigned integers
  • L0, L8, L16, L32, L64 times M0, M8, M16, M32, M64
• Reference:
  • Reference ID as unsigned integer: R8, R16, R32, R64
• Reserved types:
  • Everything <= 55 => 200 free types

Features

• Embeddable: Written in pure Lua
• Storage efficient: No duplication of strings or reference-equal tables
• Flexible: Can serialize circular references and strings containing null

Simple example

local object = ...
-- Write to file
local file = io.open(..., "w")
modlib.bluon:write(object, file)
file:close()
-- Write to text
local rope = modlib.table.rope{}
modlib.bluon:write(object, rope)
text = rope:to_text()
-- Read from text
local inputstream = modlib.text.inputstream"\1"
assert(modlib.bluon:read(object, rope) == true)

Advanced example

-- Serializes all userdata to a constant string:
local custom_bluon = bluon.new{
    aux_is_valid = function(object)
        return type(object) == "userdata"
    end,
    aux_len = function(object)
        return 1 + ("userdata"):len())
    end,
    aux_read = function(type, stream, references)
        assert(type == 100, "unsupported type")
        assert(stream:read(("userdata"):len()) == "userdata")
        return userdata()
    end,
    -- object to be written, stream providing :write(text), list of references
    aux_write = function(object, stream, references)
        assert(type(object) == "userdata")
        stream:write"\100userdata"
    end
}
-- Write to text
local rope = modlib.table.rope{}
custom_bluon:write(userdata(), rope)
assert(rope:to_text() == "\100userdata")

Schema

Place a file schema.lua in your mod, returning a schema table.

Non-string entries and minetest.conf

Suppose you have the following schema:

return {
	type = "table",
	entries = {
		[42] = {
			type = "boolean",
			description = "The Answer"
			default = true
		}
	}
}

And a user sets the following config:

mod.42 = false

It won't work, as the resulting table will be {["42"] = false} instead of {[42] = false}. In order to make this work, you have to convert the keys yourself:

return {
	type = "table",
	keys = {
		-- this will convert all keys to numbers
		type = "number"
	},
	entries = {
		[42] = {
			type = "boolean",
			description = "The Answer"
			default = true
		}
	}
}

This is best left explicit. First, you shouldn't be using numbered field keys if you want decent minetest.conf support, and second, modlib's schema module could only guess in this case, attempting conversion to number / boolean. What if both number and string field were set as possible entries? Should the string field be deleted? And so on.

Configuration

Legacy

1. Configuration is loaded from <worldpath>/config/<modname>.<extension>, the following extensions are supported and loaded (in the given order), with loaded configurations overriding properties of previous ones:
   1. json
   2. lua
   3. luon, Lua but without the return
   4. conf
2. Settings are loaded from minetest.conf and override configuration values

Locations

0. Default configuration: <modfolder>/conf.lua
1. World configuration: config/<modname>.<format>
2. Mod configuration: <modfolder>/conf.<format>
3. Minetest configuration: minetest.conf

Formats

1. lua

• Lua, with the environment being the configuration object
• field = value works
• Return new configuration object to replace

2. luon

• Single Lua literal
• Booleans, numbers, strings and tables

3. conf

• Minetest-like configuration files

4. json

• Not recommended

Versions

rolling-58

• Schema improvements & docs

rolling-57

• Uses minetest.safe_file_write for file.write

rolling-56

• Fixes math.fround
• Other minor fixes
• Switch to lazy loading
  • Do _ = modlib.<module> to avoid lag spikes at run time