8 replies to this topic

[discodancepant]

i have a section of code that repeats exactly with the logic processing, but each time with a different set of variables.

i could definetly just copy/paste my logic, and that'd work just fine, but rather than doing the easy thing, i want to learn the more efficient way.

i tried the following, with no effect;

function logic(current,maxium,next)
	if arrow == "up" then
		if (current > 1) and (current <= maximum) then
		elseif current == 1 then
			current = maximum
		elseif current == 0 then
			current = 1
		end
	elseif arrow == "down"
		if (current >= 1) and (current < maximum) then
		elseif current == maximum then
			current = 1
		elseif current == 0 then
			current = maximum
		end
	end
	return
end

i know that the code goes wrong whenever i write "current ="
but i'm not sure how to change the value of current, when current itself is a variable of an index's value.

[BigSHinyToys]

If you could give some more information about this functions purpose I might be able to help. some variables are not defined in your code.

Is this similar to the functionality you are looking for.

Spoiler

-- this is how I normaly do it
local termX,termY = term.getSize()
local posX = math.floor(termX/2)
local posY = math.floor(termY/2)
while true do
    term.clear()
    term.setCursorPos(posX,posY)
    term.write("X")
    local event = {os.pullEvent()}
    if event[1] == "key" then
	    if event[2] == 200 then -- up key
		    posY = posY - 1
	    elseif event[2] == 208 then -- down key
		    posY = posY + 1
	    elseif event[2] == 203 then -- left
		    posX = posX - 1
	    elseif event[2] == 205 then -- right
		    posX = posX + 1
	    elseif event[2] == 14 then -- Press [Backspace] key to exit
		    break
	    end
	    if posY > termY then
		    posY = termY
	    elseif posY < 1 then
		    posY = 1
	    end
	    if posX > termX then
		    posX = termX
	    elseif posX < 1 then
		    posX = 1
	    end
    end
end

[GopherAtl]

current is an argument to the function; changing it will not affect the variable that was passed into the function.

example to explain/demonstrate:

--i exists outside function...
local i=1

--function takes an arg, called i. this is unrelated to the i declared above, and effectively "hides" that i while inside the function
local function increment(i)
  i=i+1
end

--will print "1"
print(i)
increment(i)
--will still print "1"
print(i)

This could be resolved a couple of ways. The simplest is probably going to be returning the new, modified value of current at the end of the function, and catching it. Doing this with my example above would give this:

local i=1

local function increment(i)
  i=i+1
  return i
end

--will print "1"
print(i)
i=increment(i)
--will print "2" this time
print(i)

[discodancepant]

i'm trying to access a table which has all the characteristics of my menu and sub menus and the possible selections therein.

i store my current selection in another table

i then get my current level variable, the maxLevels in the current level and the next level variable.


with that i can either use my redundant logic to move between sub menus, go another layer in (sub sub menu) or exit the current sub menu, going back to the menu.

this last function i want to be variable based on current level, max level and next level, so that my code does not repeat for every possible instance of menus.

[BigSHinyToys]

Here is an example using GopherAtl method

Spoiler

local termX,termY = term.getSize()
local posX = math.floor(termX/2)
local posY = math.floor(termY/2)
local function range(nInput,nMin,nMax)
    if nInput > nMax then
	    nInput = nMax
    elseif nInput < nMin then
	    nInput = nMin
    end
    return nInput
end
while true do
    term.clear()
    term.setCursorPos(posX,posY)
    term.write("X")
    local event = {os.pullEvent()}
    if event[1] == "key" then
	    if event[2] == 200 then -- up key
		    posY = posY - 1
	    elseif event[2] == 208 then -- down key
		    posY = posY + 1
	    elseif event[2] == 203 then -- left
		    posX = posX - 1
	    elseif event[2] == 205 then -- right
		    posX = posX + 1
	    elseif event[2] == 14 then -- Press [Backspace] key to exit
		    break
	    end
	    posX = range(posX,1,termX)
	    posY = range(posY,1,termY)
    end
end

[discodancepant]

ahh, yes i see, that should help a lot.

if i don't use return (variable) then any changes i attempted to make simply don't occur globally outside of the function

is that a correct summary?

[BigSHinyToys]

variables like "strings" and "numbers" are not passed as a reference . The content of the variable is given to the function and the function works on this information then can return a variable the returned variable can be put into any variable.

local function addOne(input) -- assign the first variable passed to this function the name "input"
local input = input + 1 -- add one
return input -- return a varible
end
local nNumber = 10
local OtherNumber = addOne(nNumber)
print(nNumber)
print(OtherNumber)

functions take input's and can return an output this doesn't change the variables that were used as inputs *(with the exception of tables they work slightly different.)

[EDIT]
This explains it well.
http://stackoverflow...ue-or-reference

[GopherAtl]

yes, that is a correct summary, with one exception. tables passed in as parameters ARE changed in the original variable - unless you actually assign a new table entirely. Ex, in "function foo(argTable)", "argTable[1]='foo'" would change the original table passed in; argTable={} would not.

[discodancepant]

well, that's astoundingly helpful. Sorry if my questions seem a little noobish. I'd rather ask a dumb question than make garbage code. thanks again for the quick replies.