LibT

LibT is a collection of ComputerCraft/Lua libraries for facilitating development on ComputerCraft devices.

libt is the most basic of these libraries, and brings basic functional programming capabilities to Lua. It includes a module system for loading any other libraries in the LibT.

All LibT libraries live in the /lib directory. Configuration files live in the /etc directory.

To load libt, simply use loadfile.

local t = loadfile("libt")()

Modules

LibT includes a module system.

Use t.require(LIB) to load the library LIB (a string) by traversing a list of search paths that includes the /lib directory. Modules are cached globally in each computer, so module state persists among programs that are executed. Loading the same module twice returns the same instance.

The LibT module cache can be flushed by running libt as a program and giving it any argument, e.g. libt flush. This can be necessary when a module enters an invalid state due to a programming error.

An example LibT module isEven is defined like this:

local isEven = {
  VERSION = { 0, 0, 1, 0 }
}

function isEven.check(n)
  return n % 2 == 0
end
>>>>>>> readme; move module-specific docs to the doc subdirectory

return isEven

Key observations:

The module is a Lua table. It must include a VERSION key that is an array of 4 numbers.
Define the contents of your module -- functions, constants, etc. -- as entries in the table.
Return the table at the end of the file.

The module's table is essentially its export list. Private functions can be defined with local function foo () ... end.

Documentation

Module-specific documentation is in the doc/ subdirectory. Here is a brief overview of some of the most sophisticated libraries.

libtmsg

tput-servant was augmented with a simple messaging system, whereby sending a POST request to /msg/:id enqueues a message in the queue named :id and a GET request to /msg/:id dequeues a message from the named queue. This functionality is exposed by libtmsg. Hence, libtmsg is an alternative to libtnet that is more robust, works across any distance, and costs no ingame resources!

Basic API

send(id, msg, [contentType], [accept]) sends the given message to the queue named id. contentType and accept are used for the values of the Content-Type and Accept HTTP headers. By default, these are utf-8 plain text and *, as required by tput-servant.
recv(id, [accept]) dequeues a message from the queue named id. The value of accept is used for the HTTP Accept header, and defaults to *. Returns nil if the GET fails, or if the queue is empty.
clearMessages(id) clears the queue named id. This call cannot fail.

Advanced API

recvBlock(id, [accept], [timeout], [period], [strict]) calls recv repeatedly until a message is received. Hence, this is a polling implementation that blocks until a message is received. period controls how long to wait between polls, and defaults to 100ms. timeout is how long to wait in total because giving up and returning nil. strict is an optional flag that causes error to be used if a timeout occurs.
recvLua - same as recv but deserializes the response with t.read.
recvLuaBlock - same as recv but deserializes the response with t.read.
sendLua - same as send but serializes the request with t.show.
recvJSON
recvJSONBlock
sendJSON

librmi

Librmi is a remote method invocation library for executing code on other computers. It leverages libtmsg and libreply.

Example

To run a script on another computer, first place the script in the /rmi directory. This is where librmi looks for scripts to run remotely. Then, use the bind function to construct a proxy object for the remote machine. The remote machine must be running rmid('battery') in this case.

-- /localscript
local t = loadfile("libt")()
local rmi = t.requireStrictTg("librmi")
local battery = rmi.bind("battery")
print(t.show(battery.getBatteryInfo()))

-- /rmi/getBatteryInfo
-- actually implement logic for wrapping a battery as a peripheral and
-- extracting its info into a nice table.

Librmi caches RMI scripts with module scope. To clear the cache use rmi.clearScriptCache.

tsani/libt