Multitasking Buffering

Engineer, on 03 September 2013 - 09:05 AM said:

This most likely uses coroutines and environment manipulation. As I will not get into coroutines for this post, you might want to look that up.

So, environment manipulating, how would we do that?
It is very simple with setfenv function, it takes as arguments the function and the environment you set it to.
So, you basically have something like this for the buffering coroutine:

local bufferStack = {} -- The bufferstack
local bufferTerm = {} -- Every term api call but puts that in a stack

-- You would want to create a good system for storing your buffers, since 3 or more functions could buffer. This code is mostly pseudo code, since I dont want to create an OS :P/>/>/>

local func, err = loadfile( file )
--thats the function of  a program
-- set the fenv accordingly if the program is on the screen or not.

if programOnScreen then
	 setfenv( func, { __index = _G })
	 --run the program
end

if screenChanges then
	setfenv( func, setmetatable( { term = bufferTerm }, { __index = _G }))
	-- continue the program
end

Of course, this is not fully working etc, but you hopefully you get the point. Implementing this is a bigger task then you can expect it to be.

ElvishJerricco, on 03 September 2013 - 09:19 AM said:

Engineer, on 03 September 2013 - 09:05 AM said:

This most likely uses coroutines and environment manipulation. As I will not get into coroutines for this post, you might want to look that up.

So, environment manipulating, how would we do that?
It is very simple with setfenv function, it takes as arguments the function and the environment you set it to.
So, you basically have something like this for the buffering coroutine:

local bufferStack = {} -- The bufferstack
local bufferTerm = {} -- Every term api call but puts that in a stack

-- You would want to create a good system for storing your buffers, since 3 or more functions could buffer. This code is mostly pseudo code, since I dont want to create an OS :P/>/>/>/>/>

local func, err = loadfile( file )
--thats the function of  a program
-- set the fenv accordingly if the program is on the screen or not.

if programOnScreen then
	 setfenv( func, { __index = _G })
	 --run the program
end

if screenChanges then
	setfenv( func, setmetatable( { term = bufferTerm }, { __index = _G }))
	-- continue the program
end

Of course, this is not fully working etc, but you hopefully you get the point. Implementing this is a bigger task then you can expect it to be.

Won't work. You're changing what term is for the file, but not for functions like write()

function write( sText )
	local w,h = term.getSize()		
	local x,y = term.getCursorPos()
	
	local nLinesPrinted = 0
	local function newLine()
		if y + 1 <= h then
			term.setCursorPos(1, y + 1)
		else
			term.setCursorPos(1, h)
			term.scroll(1)
		end
		x, y = term.getCursorPos()
		nLinesPrinted = nLinesPrinted + 1
	end
	
	-- Print the line with proper word wrapping
	while string.len(sText) > 0 do
		local whitespace = string.match( sText, "^[ \t]+" )
		if whitespace then
			-- Print whitespace
			term.write( whitespace )
			x,y = term.getCursorPos()
			sText = string.sub( sText, string.len(whitespace) + 1 )
		end
		
		local newline = string.match( sText, "^\n" )
		if newline then
			-- Print newlines
			newLine()
			sText = string.sub( sText, 2 )
		end
		
		local text = string.match( sText, "^[^ \t\n]+" )
		if text then
			sText = string.sub( sText, string.len(text) + 1 )
			if string.len(text) > w then
				-- Print a multiline word				
				while string.len( text ) > 0 do
					if x > w then
						newLine()
					end
					term.write( text ) -- huh?
					text = string.sub( text, (w-x) + 2 )
					x,y = term.getCursorPos()
				end
			else
				-- Print a word normally
				if x + string.len(text) - 1 > w then
					newLine()
				end
				term.write( text ) -- Oh, whats here?
				x,y = term.getCursorPos()
			end
		end
	end
	
	return nLinesPrinted
end

function print( ... )
	local nLinesPrinted = 0
	for n,v in ipairs( { ... } ) do
		nLinesPrinted = nLinesPrinted + write( tostring( v ) ) -- uses write! what a surprise!
	end
	nLinesPrinted = nLinesPrinted + write( "\n" )
	return nLinesPrinted
end

Engineer, on 03 September 2013 - 09:41 AM said:

I didnt see your post when I did that.

os.loadAPI("framebuffer")
w,h = term.getSize()
buffer = framebuffer.new(w,h,colors.black)
term.redirect(buffer)
print("Hello")
term.restore()

PrinzJuliano, on 04 September 2013 - 11:22 AM said:

Can you just show me how i create a multitasking program running two programs?

Lyqyd said:

Here in Ask a Pro, the effort people are willing to expend helping you is usually about equal to the effort you are putting in.

function hello()
   print "Hello"
   coroutine.yield()
   print "World!"
end

co = coroutine.create(hello)

coroutine.resume(co)

coroutine.resume(co)

failed to resume a dead coroutine