Preserve, improve environment and replace userdata

* Preserve the environment table so that it must
only be regenerated after a game restart, after
a computer is restarted, and at the tiem of the
initialization of a computer.
* Replace the current meta-based userdata
mechanisms with a global `ram` variable within the
environment, as the preservation of the environment
itself causes its global variables to be preserved
as well
* Make `get_attr` convert meta to a table before
accessing the requested key in order to ensure that
the meta can be correctly accessed even if it is
not a string
* Initialize output_editable meta on node place

.luacheckrc

@@ -5,6 +5,9 @@ globals = {
 	"minetest",
 	"jit",
 	"digicompute",
+
+	-- OctOS Internals
+	"ram",
 }
 
 read_globals = {
@@ -21,6 +24,6 @@ read_globals = {
 	-- OctOS Internals (custom environment functions)
 	"set_help", "get_attr", "get_output", "set_output",
 	"set_output_editable", "get_input", "set_input",
-	"get_os", "set_os", "get_userdata", "set_userdata",
-	"refresh", "run", "loadstring", "set_run", "fs",
+	"get_os", "set_os", "refresh", "run", "loadstring",
+	"set_run", "fs",
 }

doc/computers/os_api.md

@@ -1,6 +1,10 @@
 # OctOS
 OctOS is the operating system used by digicomputers. OctOS is made of many Linux-like commands which are documented in `commands.md`, however, there is also an API which can be used when writing programs for OctOS. The API can be used by players to interact with the computer under a safe and secure environment. The documentation is divided into two sections as is the code, main (for general functions), and filesystem (for filesystem access).
 
+## Accessing the RAM (userdata)
+
+In earlier versions of digicompute, a RAM-like storage mechanism could be accessed with a `get_userdata` and `set_userdata` API. However, this API was later removed and instead the RAM is accessed by setting values of the `ram` table within the environment. Data can also be preserved by setting a global variable within the environment, however, use of the `ram` table is recommended. This is because of how digicompute handles the environments in the background. Global variables, including the `ram` table, are stored within the environment itself, and with the environment being preserved until the computer is shut off or deinitialized, the variables are preserved as well.  Please note that digicompute does not currently have a completely accurate representation of RAM, in that there is no limitation to the amount of data that can be stored.
+
 ## Main
 This contains a set of functions mainly for the purpose of interacting with the computer's displays.
 
@@ -23,6 +27,9 @@ Gets a piece of global information from the node meta (storage). Several common
 * `input`: input field.
 * `output`: output buffer.
 * `name`: computer name.
+* `help`: formspec help text.
+* `id`: computer id.
+* `output_editable`: whether the output buffer is editable.
 
 #### `get_output()`
 **Usage:** `get_output()`
@@ -64,16 +71,6 @@ Sets a piece of information stored in the OS table. This table stores basic valu
 * `reboot`: command to reboot the computer.
 * `prefix`: prefix printed at the beginning of a new line.
 
-#### `get_userdata(key)`
-**Usage:** `get_userdata(<data name (string)>)`
-
-Gets a piece of information from the userdata table. This table is like RAM, as information will be reset when the computer is turned off.
-
-#### `set_userdata(key, value)`
-**Usage:** `set_userdata(<data name (string)>, <value>`
-
-Stores any piece of information in the non-persistant userdata table. (Table is cleared when computer is turned off, therefore non-persistant.)
-
 #### `refresh()`
 **Usage:** `refresh()`
 

modules/computers/api.lua

@@ -5,6 +5,8 @@ digicompute.c = {}
 local path      = digicompute.path
 local main_path = path.."computers/"
 
+local environments = {}
+
 -- Make computer directory
 digicompute.builtin.mkdir(main_path)
 
@@ -374,8 +376,13 @@ function digicompute.c:deinit(pos, clear_entry)
 			end
 	end
 
+	local id = meta:get_string("id")
+	-- Remove saved environment
+	if environments[id] then
+		environments[id] = nil
+	end
+
 	if clear_entry ~= false then
-		local id = meta:get_string("id")
 		computers[id] = nil
 	end
 end
@@ -429,6 +436,7 @@ end
 function digicompute.c:off(pos, player)
 	local temp = minetest.get_node(pos) -- Get basic node information
 	local offname = "digicompute:"..minetest.registered_nodes[temp.name].digicompute.base
+	local meta = minetest.get_meta(pos)
 	-- Swap node to off
 	minetest.swap_node({x = pos.x, y = pos.y, z = pos.z}, {name = offname, param2 = temp.param2})
 	-- Update infotext
@@ -437,8 +445,13 @@ function digicompute.c:off(pos, player)
 	if player and player.get_player_name then
 		minetest.close_formspec(player:get_player_name(), "")
 	end
-	-- Clear update buffer
-	minetest.get_meta(pos):set_string("output", "")
+	-- Clear output buffer
+	meta:set_string("output", "")
+	-- Reset environment
+	local id = meta:get_string("id")
+	if environments[id] then
+		environments[id] = nil
+	end
 end
 
 -- [function] reboot computer
@@ -455,6 +468,13 @@ end
 function digicompute.c:make_env(pos)
 	assert(pos, "digicompute.c:make_env missing position")
 	local meta = minetest.get_meta(pos)
+	local id = meta:get_string("id")
+
+	-- if an environment for this computer has already been generated, return it instead
+	if environments[id] then
+		return environments[id]
+	end
+
 	local cpath = meta:get_string("path")
 
 	-- Main Environment Functions
@@ -484,7 +504,7 @@ function digicompute.c:make_env(pos)
 	end
 	-- [function] get attribute
 	function main.get_attr(key)
-		return meta:get_string(key) or nil
+		return meta:to_table().fields[key] or nil
 	end
 	-- [function] get output
 	function main.get_output()
@@ -531,17 +551,6 @@ function digicompute.c:make_env(pos)
 			return false
 		end
 	end
-	-- [function] get userdata value
-	function main.get_userdata(key)
-		local res = meta:get_string("userdata")
-		return minetest.deserialize(res)[key] or nil
-	end
-	-- [function] set userdata value
-	function main.set_userdata(key, value)
-		local table = minetest.deserialize(meta:get_string("userdata")) or {}
-		table[key] = value
-		return meta:set_string("userdata", minetest.serialize(table))
-	end
 	-- [function] refresh
 	function main.refresh()
 		local current_user = meta:get_string("current_user")
@@ -636,7 +645,10 @@ function digicompute.c:make_env(pos)
 		env[k] = v
 	end
 
-	return env
+	env.ram = {} -- RAM table, replacement for userdata
+
+	environments[id] = env
+	return environments[id]
 end
 
 -- [function] run code
@@ -680,8 +692,8 @@ function digicompute.register_computer(itemstring, def)
 			meta:set_string("input", "")                               -- Initialize input buffer
 			meta:set_string("output", "")                              -- Initialize output buffer
 			meta:set_string("os", "")                                  -- Initialize OS table
-			meta:set_string("userdata", "")                           -- Initialize userdata table
 			meta:set_string("help", "Type a command and press enter.") -- Initialize help
+			meta:set_string("output_editable", "false")                -- Initialize uneditable output
 			digicompute.c:new_id(pos)                                  -- Set up ID
 
 			-- Update infotext

octos/exec/help.lua

@@ -1,8 +1,8 @@
 -- cmd: help --
 
 local params = ...
-local bin    = get_userdata("bin")
 local param  = params[1]
+local bin = ram.bin
 
 --[local function] Sort the help list alphabetically
 local function sort(list)

octos/exec/nano.lua

@@ -1,24 +1,24 @@
 if get_attr("run") == "os/exec/nano.lua" then
 	local input = get_attr("input")
 	if input == "save" then
-		fs.write(get_userdata("nano:path"), get_output(), "w")
+		fs.write(ram.nano_path, get_output(), "w")
 	elseif input == "discard" or input == "exit" then
 		if input == "exit" then
-			fs.write(get_userdata("nano:path"), get_output(), "w")
+			fs.write(ram.nano_path, get_output(), "w")
 		end
 
-		set_userdata("nano:path", nil) -- Clear nano path
-		set_os("prefix", get_userdata("nano:prefix")) -- Restore prefix
-		set_userdata("nano:prefix", nil) -- Clear stored prefix
-		set_output(get_userdata("nano:output").."\n"..get_os("prefix")) -- Restore output
-		set_userdata("nano:output", nil) -- Clear stored output
+		ram.nano_path = nil -- Clear nano path
+		set_os("prefix", ram.nano_prefix) -- Restore prefix
+		ram.nano_prefix = nil -- Clear stored prefix
+		set_output(ram.nano_output.."\n"..get_os("prefix")) -- Restore output
+		ram.nano_output = nil -- Clear stored output
 		set_run() -- Clear custom run file
 
 		-- Restore "output editable" to previous state
-		if not get_userdata("nano:output_was_editable") then
+		if not ram.nano_output_was_editable then
 			set_output_editable(false)
 		else
-			set_userdata("nano:output_was_editable", nil)
+			ram.nano_output_was_editable = nil
 		end
 	end
 
@@ -31,10 +31,10 @@ else
 	if path then
 		local contents = fs.read(path) or ""
 
-		set_userdata("nano:path", path) -- Store editing path for later
-		set_userdata("nano:output", get_output()) -- Store old output for later
+		ram.nano_path = path -- Store editing path for later
+		ram.nano_output = get_output() -- Store old output for later
 		set_output(contents) -- Set output to contents of file or blank
-		set_userdata("nano:prefix", get_os("prefix")) -- Store OS prefix for later
+		ram.nano_prefix = get_os("prefix") -- Store OS prefix for later
 		set_os("prefix", "") -- Set OS prefix to a blank string
 		set_help("\"save\" to save, \"discard\" to discard and exit, \"exit\" to save and exit") -- Add information to help
 		set_run("os/exec/nano.lua") -- Set run file to the nano executable
@@ -43,7 +43,7 @@ else
 		if get_attr("output_editable") == "false" then
 			set_output_editable(true)
 		else
-			set_userdata("nano:output_was_editable", "true")
+			ram.nano_output_was_editable = true
 		end
 
 		refresh() -- Refresh formspec

octos/main.lua

@@ -1,5 +1,5 @@
 local input = get_attr("input"):split(" ")
-local bin   = get_userdata("bin")
+local bin = ram.bin
 
 if input[1] ~= "" then
 	print(get_attr("input"), false)

octos/start.lua

@@ -27,7 +27,7 @@ bin[get_os("off")] = { description = "Turn off computer" } -- Turn off computer
 bin[get_os("reboot")] = { description = "Reboot computer" } -- Reboot computer
 
 -- Save bin table
-set_userdata("bin", bin)
+ram.bin = bin
 
 -- Set initial output value
 set_output("Welcome to octOS version 0.2.\n\n"..get_os("prefix")) -- print welcome