So I was talking with a colleague today about lua, closures, dynamic binding, etc, and it came up that a bit of code I used in my UI mod is actually pretty nifty, and surprising that it works at all.

Basically I dynamically create a variable number of UI panels (one for each area that has a battle going on). This dynamic UI presents a problem of how to handle mouse interaction events. The mouse events do not include a reference to the UI panel that was interacted with, so I need to essentially store in my mouse event what panel was clicked on. To do this I simply came up with a redirection scheme where I register OnMouseEvent1, OnMouveEvent2, etc. Then call RealOnMouseEvent(1), etc. I could just define a bunch of OnMouseEventX functions, but that’s boring. So I came up with this gem. Apparently this is *NOT* how any other language behaves.

In the code below the functions retain the value of “i” at the time they were defined. So I end up with several functions that call RealOnMsOvr with the values of 1, 2, 3, 4, to g_maxPanels. This would not work in most other languages.

Background:
CoW is my “class” where all my functions are declared.
“i” is not declared before this statement.
Names in the code have been shortened to fit in this post.

for i=1,g_maxPanels do

        W.Status[i] = {}

        e = W(“Blackframe”)

        e:Resize(180, 60)

        e:Alpha(0.7)            

        – Register window events for this panel

        CoW["OnMsOvr"..tostring(i)] = function(…) CoW.RealOnMsOvr(i) end

        CoW["OnLBtnUp"..tostring(i)] = function(…) CoW.RealOnLBtnUp(i) end

        CoW["OnRBtnUp"..tostring(i)] = function(…) CoW.RealOnRBtnUp(i) end 

        WinRegCrEvHnd(e.name, “OnMsOvr”, “CoW.OnMsOvr”..tostring(i));

        WinRegCrEvHnd(e.name, “OnLBtnUp”, “CoW.OnLBtnUp”..tostring(i));

        WinRegCrEvHnd(e.name, “OnRBtnUp”, “CoW.OnRBtnUp”..tostring(i));

        W.Status[i].Frame = e   

        –More UI code

        –More UI code

        –More UI code

end

Si te cansaste de la interfaz de este lector de feeds gratuito, ahora puedes modificarla sin mayores sustos. Tan simple como montar la imagen “dmg”, y clicar en el ejecutable. Sólo tiene un pero, y es que funciona nada más con la versión 2.1.2. Y como la que tengo es la 2.2.nosecuantos, no puedo decir si queda mejor o peor, o si da algún tipo de problema (que es de esperar que no).

Si alguno lo prueba, que me lo comente =).

Fuente | Infinise Design