How to make a button API - arrays

Question

I am trying to make an easy to use button API in Lua with ComputerCraft, and I'm having some trouble. When I do:
os.loadAPI("button")
action=function()
term.clear()
term.setCursorPos(1,1)
print("Hello!")
end
button.newButton("B1",5,5,20,10)
button.drawButton("B1",colors.orange,colors.white)
button.onClick("B1",action,true)
Nothing happens, it doesn't even draw the colors. I have done tests, and when I store something like colors.white as a variable, then print the variable, it returns the number code of that color, which comes from the colors API. Here is what I have:
--to use the newButton function, do this:
--button.newButton(exampleButton)
--to use onClick function, create a variable like this:
--exampleFunc=function()
--(code)
--end
--Then call onClick with the same variable:
--button.onClick(exampleButton,exampleFunc)
buttons={}
xPos=0
yPos=0
function removeButton(buttonName)
for key, fields in pairs(buttons) do
if key == buttonName then
table.remove(button,buttonName)
else
print("ERROR: button name not available")
end
end
end
function onClick(buttonName,action,boolean)
for key, fields in pairs(buttons) do
if boolean then
testClick(action)
end
end
end
function drawSeparateButton(x,y,w,h,outLineColor,fillColor)
if key == buttonName then
x=buttons[buttonName]["x"]
y=buttons[buttonName]["y"]
w=buttons[buttonName]["w"]
h=buttons[buttonName]["h"]
paintutils.drawBox(x,y,x+(w-1),y+(h-1),outLineColor)
paintutils.drawFilledBox(x+1,y+1,x+(w-2),y+(h-2),fillColor)
end
end
function testClick(action)
for key, fields in ipairs(buttons) do
x=buttons[buttonName]["x"]
y=buttons[buttonName]["y"]
w=buttons[buttonName]["w"]
h=buttons[buttonName]["h"]
x2=x+(w-1)
y2=y+(h-1)
button,xPos,yPos=os.pullEvent("mouse_click")
if xPos>=x and xPos<=x2 and yPos>=y and yPos<=y2 then
action()
end
end
end
function newButton(buttonName,X,Y,W,H)
buttons[buttonName] = {x=X,y=Y,w=W,h=H}
end
function drawButton(buttonName,outLineColor,fillColor)
for key, fields in ipairs(buttons) do
if key == buttonName then
x=buttons[buttonName]["x"]
y=buttons[buttonName]["y"]
w=buttons[buttonName]["w"]
h=buttons[buttonName]["h"]
x2=x+w-1
y2=y+h-1
x3=x+1
y3=y+1
x4=x+w-2
y4=y+h-2
paintutils.drawBox(x,y,x2,y2,outLineColor)
paintutils.drawFilledBox(x3,y3,x4,y4,fillColor)
elseif key ~= buttonName then
print("Button name not availabel")
end
end
end
I just need to be able to store a color like colors.white in a variable and have it returned as colors.white, and not the color code. I also need to be able to check which button is clicked and run a function specified by the user when one of the buttons are clicked.

Answer 1

I'm going to walk through your prototype code and point out some errors I see and also try to answer your question. I'm going to assume that you want to set a key value in a table to an array and access that externally.
A quick and short answer to your question is that you can store tables within tables and access them through keys or indices. A design change I would make, however, is to store your exampleFunc as a member of each button table to associate it with a specific button.
Example:
buttons = {}
buttons.playButton = {x=0, y=0, w=10, h=10, func=function() return end}
buttons.quitButton = {x=0, y=30, w=10, h=10, func=function() return end}
...
buttons.quitButton.x = 10
buttons.playButton.func()
Tables have a key-value structure, where keys can be strings or numbers. There are multiple ways to access an array using a key depending on the data type of the key.
For example, instead of writing buttons.quitButton.x = 10 we could've written buttons["quitButton"].x = 10 or buttons["quitButton"]["x"] = 10 or buttons.quitButton["x"] = 10.
This page is a great starting point for learning about Lua's tables.
According to this page, os.pullEvent() is blocking, and you will only be able to check if one button is clicked per mouse click. Consider looping through your buttons table and checking every button to see if the mouse falls within its rectangular bounds. Once you find which button the mouse clicked, you can call its func member. While we're still discussing this method, the while true do loop is completely unnecessary.
function removeButton(buttonName)
for buttonName in pairs(button) do
...
function newButton(buttonName)
state=true
for buttonName in pairs(buttons) do
...
You may come from a Python background where the statement if element in list exists but Lua has no such statement. The for loops you use are looping through every member of the list. You also aren't capturing all of the variables returned by the pairs() function. A fix for that would look something like the following:
function buttonFunction(buttonName)
for key, fields in pairs(buttons) do
if key == buttonName then
...
end
end
There are multiple instances where you refer to the variable button when you mean buttons.