Toggling a (string) variable with Lua

[poiru]

Here is a simple method to toggle between two strings (e.g. "show" and "hide") and a demonstration of using !CommandMeasure with Lua:

Skin:

Code: Select all

[Variables]
state=hide

[mLua]
Measure=Script
ScriptFile=Test.lua

...

LeftMouseUpAction=!Execute [!CommandMeasure "mLua" "ToggleVariable('state', 'hide', 'show')"]

Lua:

Code: Select all

function ToggleVariable(name, a, b)
	-- Set str to b if #name# is a, or to a otherwise
	local str
	if SKIN:GetVariable(name) == a then
		str = b
	else
		str = a
	end

	-- Set #name# to str
	SKIN:Bang('!SetVariable "' .. name .. '" "' .. str .. '"')
end

(For a more compact and faster version, use this)

The example above will toggle #state# between hide and show.

[smurfier]

I'm not in a position to test, but I used something similar in LuaCalendar.

Code: Select all

function ToggleVariable(name, a, b)
   SKIN:Bang('!SetVariable "' .. name .. '" "' .. (SKIN:GetVariable(name)==a and b or a) .. '"')
end

[jsmorley]

I use a similar approach with a weather skin that toggles the display from Fahrenheit to Celsius every 10 seconds...

Code: Select all

	if string.upper(StartingUnit) == "F" then

		if CurrentUnit == "F" then
			CurrentUnit = "C"
			ConvertedTemp = round((5/9)*(ConvertedTemp-32))
			SKIN:Bang("!SetVariable TempColor "..CColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		else
			CurrentUnit = "F"		
			SKIN:Bang("!SetVariable TempColor "..FColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		end
	
	elseif string.upper(StartingUnit) == "C" then
	
		if CurrentUnit == "C" then
			CurrentUnit = "F"
			ConvertedTemp = round((9/5)*ConvertedTemp+32)
			SKIN:Bang("!SetVariable TempColor "..FColor)			
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		else
			CurrentUnit = "C"		
			SKIN:Bang("!SetVariable TempColor "..CColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		end	

	end

[poiru]

I'm not in a position to test, but I used something similar in LuaCalendar.

Code: Select all

function ToggleVariable(name, a, b)
   SKIN:Bang('!SetVariable "' .. name .. '" "' .. (SKIN:GetVariable(name)==a and b or a) .. '"')
end

Yep, that does indeed work and is better in terms of performance (edited first post to point to it). Thanks!

I use a similar approach with a weather skin that toggles the display from Fahrenheit to Celsius every 10 seconds...

Yeah, a rather basic example, but perfect for showing how !CommandMeasure works with the Script measure.

[jsmorley]

Yep, that does indeed work and is better than my code (edited first post to point to it). Thanks!

I both agree and disagree. The "shorthand" approach is nice, and I recommend it. Once you get used to it it does make tighter and more efficient code. However, the result is the same and I could argue that the If then else approach is more "accessible" to a user not steeped in programming in languages like C or Java when you are demonstrating something. Any "efficiencies" achieved by using the shorthand approach are going to be completely negligible in a few lines of code.

[MerlinTheRed]

I use a similar approach with a weather skin that toggles the display from Fahrenheit to Celsius every 10 seconds...

Code: Select all

	if string.upper(StartingUnit) == "F" then

		if CurrentUnit == "F" then
			CurrentUnit = "C"
			ConvertedTemp = round((5/9)*(ConvertedTemp-32))
			SKIN:Bang("!SetVariable TempColor "..CColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		else
			CurrentUnit = "F"		
			SKIN:Bang("!SetVariable TempColor "..FColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		end
	
	elseif string.upper(StartingUnit) == "C" then
	
		if CurrentUnit == "C" then
			CurrentUnit = "F"
			ConvertedTemp = round((9/5)*ConvertedTemp+32)
			SKIN:Bang("!SetVariable TempColor "..FColor)			
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		else
			CurrentUnit = "C"		
			SKIN:Bang("!SetVariable TempColor "..CColor)
			SKIN:Bang("!SetVariable TempText "..ConvertedTemp.."°"..CurrentUnit)
		end	

	end

You do get ConvertedTemp from a reliable source each time before this part of the code is run, right? Otherwise I imagine you'd get a hell of a lot of roundoff errors when it's converted back and forth many times.

[jsmorley]

You do get ConvertedTemp from a reliable source each time before this part of the code is run, right? Otherwise I imagine you'd get a hell of a lot of roundoff errors when it's converted back and forth many times.

ConvertedTemp is retrieved as a whole number from the skin on each Update() and the Lua does not update that number with any converted values. The value is never "rounded" twice.