Build Scripts

To support native dependencies, lde supports build scripts. These are stored at the root of your package, named build.lua.

If one is present, instead of symlinking your src directory to your target directory, lde will copy your source folder into target, and then run the build script to populate the newly created dir.

This allows you to do things like preprocess your files, pull in and compile a C module for use in lua, etc. This is all accomplished using the lde-build API.

Caching

A build script runs only when its inputs change. lde records the size, mtime, and hash of every file under src/, plus lde.json and build.lua. An unchanged package skips the build script and keeps the previous output.

Examples

Native module

This example downloads a C source file, compiles it, and places the resulting .so next to the package entry point:

local build = require("lde-build")

local source = build:fetch("https://example.com/foo.c")
build:write("foo.c", source)
build:cc({ "-c", build.outDir .. "/foo.c", "-o", build.outDir .. "/foo.o" })
build:cc({ build.outDir .. "/foo.o", "-o", build.outDir .. "/foo.so" })

Preprocessing

This example is used in the hood graphics library to include C header files into ffi.cdefs:

local build = require("lde-build")

local init = build:read("init.lua")

local escapes = {
	["\\"] = "\\\\",
	["\""] = "\\\"",
	["\n"] = "\\n",
	["\r"] = "\\r",
	["\t"] = "\\t"
}

local preprocessed = string.gsub(init, "%[%[#embed \"([^\"]+)\"%]%]", function(filename)
	local content = build:read(filename)
	return '"' .. (content:gsub("[\\\"\n\r\t]", escapes)) .. '"'
end)

build:write("init.lua", preprocessed)