Can you explain me how works Lua?

[HerlySQR]

I'm getting started in Lua after 4 months of learning Jass and vJass, I know some basics things like I can't use the words "call", "set", "takes" or "returns", for code functions I can do it inside of the current function, the IDs needs FourCC and all the variables can have any type of value, I will ask you what I need when I consider it necessary, to start I wanna ask how to init a trigger, and to reffer it in another trigger do I need create a global variable for it?

 

[Uncle]

function CreateTriggerExample()

    local trig = CreateTrigger() -- local variable storing the trigger
    TriggerRegisterAnyUnitEventBJ(trig, EVENT_PLAYER_UNIT_SPELL_CAST)
    TriggerAddAction(trig, function () -- with lua you don't even need to create a function outside of this one for the Conditions/Actions
        local u = GetTriggerUnit()
        KillUnit(u)
    end)

    myGlobalTrig = CreateTrigger() -- global variable storing the trigger
    TriggerRegisterAnyUnitEventBJ(myGlobalTrig, EVENT_PLAYER_UNIT_SPELL_CAST)
    TriggerAddAction(trig, function () -- with lua you don't even need to create a function outside of this one for the Conditions/Actions
        local u = GetTriggerUnit()
        KillUnit(u)
    end)

end

function SomeOtherFunction()
    DestroyTrigger(myGlobalTrig)
end

It's basically the same thing as Jass but with less limitations.

So just call CreateTriggerExample() and the above triggers will be created. If you wanted to destroy your trigger at a later time or in another function you can store it in a global variable and reference it like you normally would.

The nice thing about Lua is that you can do everything inside of a single function (no need for a separate callback function and dealing with globals to pass information between the two).

You can make much better use of local variables since these can be referenced more easily. For example:

function OtherExample()

    local u = CreateUnit(id, unitid, x, y, face) -- i'm creating a unit outside of our trigger

    local trig = CreateTrigger()
    TriggerRegisterAnyUnitEventBJ(trig, EVENT_PLAYER_UNIT_SPELL_CAST)
    TriggerAddAction(trig, function ()
        KillUnit(u) -- and i'm referencing the created unit inside of the actions of this trigger
    end)

end

Then for making everything easier to initialize you can use this: [Lua] Global Initialization

 

[HerlySQR]

Thank you for answer.

You can make much better use of local variables since these can be referenced more easily. For example:

Wow, so its even better than I thought

Then for making everything easier to initialize you can use this: [Lua] Global Initialization

It is not clear to me what I have to do, I just have to add this code or I have to do this manually?

 

[Uncle]

To be honest I never bothered using Global Initialization. I would create a function that runs all of my other functions, and call it in the trigger editor:

• Events:
• Game - Elapsed game time is 0.50 seconds
• Actions:
• Custom script: GameSetup()

So I'd have a function called GameSetup which called of my other functions.

function GameSetup()
    SetupUnits()
    SetupPlayers()
    SetItems()
    -- etc
end

Maybe the newbie way of doing it but it works.

 

[HerlySQR]

To be honest I never bothered using Global Initialization. I would create a function that runs all of my other functions, and call it in the trigger editor:

• Events:
• Game - Elapsed game time is 0.50 seconds
• Actions:
• Custom script: GameSetup()

So I'd have a function called GameSetup which called of my other functions.

function GameSetup()
    SetupUnits()
    SetupPlayers()
    SetItems()
    -- etc
end

Maybe the newbie way of doing it but it works.

Je, so I will ask them XD

 

[Uncle]

I think you may be able to do something like this as well:

do
    SetupUnits()
    SetupPlayers()
    SetItems()
    -- etc
end

 

[HerlySQR]

I think you may be able to do something like this as well:

do
    SetupUnits()
    SetupPlayers()
    SetItems()
    -- etc
end

I think thats how I can do libraries, then this my next question, what is the equivalent in Lua to libraries and structs?

 

[Uncle]

Not sure about Libraries but Lua uses Tables for just about everything. You should read through the Lua manual and look into it (v5.3).

Here's a Table that mimics a Struct:

person = {
  age = 18,
  name = "bob",
  height = "5'10",
}

print(person.age, person.name, person.height) -- display our persons age, name, and height

Also, there's no reason you have to code in pure Lua, check this out: [General] - is JESP still a thing?

I'm currently coding my maps in c# -> Orden4/WCSharp

 

[HerlySQR]

Not sure about Libraries but Lua uses Tables for just about everything. You should read through the Lua manual and look into it (v5.3).

Oh, I see thank you.

Also, there's no reason you have to code in pure Lua, check this out: [General] - is JESP still a thing?

I'm currently coding my maps in c# -> Orden4/WCSharp

I wanna go step by step.

 

[HerlySQR]

One more thing, what does "do"?

 

[Uncle]

One more thing, what does "do"?

Here's what Do is used for in Lua:
Why use a do-end block in Lua?

I was under the impression it would just DO the code inside, like call it automatically, but I was wrong.

I recommend taking a look at Tasyen's code, for example check out this resource of his: TasItemshop

It looks like he Hooks into some of Blizzard's functions like InitBlizzard() and has his functions run then.

do
    local real = InitBlizzard
    function InitBlizzard()
        real()
        -- put your code here:
        print("Hello World")
    end
end

Again, he's Hooking into an existing Blizzard function MarkGameStarted(), he does this to avoid Desyncs that seem to happen when code is run before all players have finished loading:

-- in 1.31 and up to 1.32.9 PTR (when I wrote this) Frames are not correctly saved and loaded, breaking the game.
-- This runs all functions added to it with a 0s delay after the game has loaded.
do
    local data = {}
    local real = MarkGameStarted
    local timer
 
    function FrameLoaderAdd(func)
        table.insert(data, func)
    end

    function MarkGameStarted()
        real()
        local trigger = CreateTrigger()
        timer = CreateTimer()
        TriggerRegisterGameEvent(trigger, EVENT_GAME_LOADED)
        TriggerAddAction(trigger, function()
            TimerStart(timer, 0, false, function()
                xpcall(function()
                for _,v in ipairs(data) do v() end
                end, print)
            end)
        end)
    end
end

I read some more about Global Initialization and I think it causes Desyncs at the moment due to an issue with Pairs. "Currently the iteration with pairs is not synced in multiplayer."

So I would try the above solutions that Taysen has been using in his resources (he seems to understand all of this better than anyone else). Or, maybe Bribe has a new version of Global Initialization that doesn't use Pairs.

 

[HerlySQR]

Not sure about Libraries but Lua uses Tables for just about everything. You should read through the Lua manual and look into it (v5.3).

Here's a Table that mimics a Struct:

person = {
  age = 18,
  name = "bob",
  height = "5'10",
}

print(person.age, person.name, person.height) -- display our persons age, name, and height

Also, there's no reason you have to code in pure Lua, check this out: [General] - is JESP still a thing?

I'm currently coding my maps in c# -> Orden4/WCSharp

After learning a lot of things about lua, I couldn't find the way to do a struct like in vJass, and your example is a determinated table and not a struct that I can use as a variable, or Am I wrong?, if not, can you help me to know how to do a struct like vJass?

 

[Elprede]

You could code something like this for structs in Lua.

Struct Example

object = {}

function object.new()
   -- Create a table
   local self = {}
 
   -- Methods
   function self.set(field, value)
       self[field] = value
   end
   function self.get(field)
       return self[field]
   end

   return self
end

-- Testing
spell = object.new()
spell.set('nfcc', 50)
print(spell.get('nfcc'))

Struct Example 2

object = {}

-- Methods
function object.new()
   local o = {}
   setmetatable(o, self)
   self.stack[o] = o
   return o
end
function object.set(field, value)
   -- self here refers to the struct instance
   self[field] = value
end
function object.get(field)
   return self[field]
end

-- Test
spell = object.new()
spell.set('nfcc', 10)
print(spell.get('nfcc'))

 

[HerlySQR]

@GhostHunter123 thank you, but I tried more and I got the way to do it and I translated an struct I made in vJass (I though I had posted explaining it but well) I will share you to you can check it if is ok.

Spoiler: Struct vJass

library Revive initializer Init requires TimerUtils

globals
    integer array Revive_Instance
endglobals

struct Revive
   
    unit hero
    timer revive
    timerdialog clock
   
    static method create takes unit hero returns thistype
        local thistype this=thistype.allocate()
        set this.hero=hero
        set this.revive=NewTimerEx(this)
        call TimerStart(this.revive,15.00+5.00*I2R(R2I(SquareRoot(I2R(GetHeroLevel(hero))))),false,function thistype.end_revive)
        set this.clock=CreateTimerDialog(this.revive)
        call TimerDialogSetTitle(this.clock,"You revive in: ")
        if LocalPlayer==GetOwningPlayer(hero) then
            call TimerDialogDisplay(this.clock,true)
        endif
        return this
    endmethod
   
    static method end_revive takes nothing returns nothing
        local Revive this=GetTimerData(GetExpiredTimer())
        call this.destroy()
    endmethod
   
    method destroy takes nothing returns nothing
        local location l
        call DestroyTimerDialog(this.clock)
        call ReleaseTimer(this.revive)
        if IsPlayerInForce(GetOwningPlayer(this.hero),udg_Grupo_Draeneanos) then
            set l=GetRandomLocInRect(udg_Draeneanos)
        else
            set l=GetRandomLocInRect(udg_Demonios)
        endif
        call ReviveHeroLoc(this.hero,l,true)
        call RemoveLocation(l)
        set l=null
        set this.hero=null
        set this.revive=null
        set this.clock=null
        call this.deallocate()
    endmethod
endstruct

private function Conditions_borrar takes nothing returns boolean
    return IsUnitType(udg_UDexUnits[udg_UDex],UNIT_TYPE_HERO)
endfunction

private function Actions_borrar takes nothing returns nothing
    local Revive t=Revive_Instance[udg_UDex]
    call t.destroy()
endfunction

//-- --

private function Conditions takes nothing returns boolean
    return IsUnitType(GetDyingUnit(),UNIT_TYPE_HERO)
endfunction

private function Actions takes nothing returns nothing
    set Revive_Instance[GetUnitUserData(GetDyingUnit())]=Revive.create(GetDyingUnit())
endfunction

//===========================================================================
private function Init takes nothing returns nothing
    local trigger t=CreateTrigger()
    call TriggerRegisterVariableEvent(t,"udg_UnitIndexEvent",EQUAL,2.00)
    call TriggerAddCondition(t,Condition(function Conditions_borrar))
    call TriggerAddAction(t,function Actions_borrar)
    set t=null
    //-- --
    set gg_trg_Si_mueres_Heroe=CreateTrigger()
    call DisableTrigger(gg_trg_Si_mueres_Heroe)
    call TriggerRegisterAnyUnitEventBJ(gg_trg_Si_mueres_Heroe,EVENT_PLAYER_UNIT_DEATH)
    call TriggerAddCondition(gg_trg_Si_mueres_Heroe,Condition(function Conditions))
    call TriggerAddAction(gg_trg_Si_mueres_Heroe,function Actions)
endfunction
endlibrary

Spoiler: Struct Lua

do
    gg_trg_Si_mueres_Heroe=CreateTrigger()
    Revive_Instance={}

    Revive={

        end_revive=function()
            Revive.destroy(GetTimerData())
        end,
       
        destroy=function(this)
            local l
            DestroyTimerDialog(this.clock)
            ReleaseTimer(this.revive)
            if IsPlayerInForce(GetOwningPlayer(this.hero),udg_Grupo_Draeneanos) then
                l=GetRandomLocInRect(udg_Draeneanos)
            else
                l=GetRandomLocInRect(udg_Demonios)
            end
            ReviveHeroLoc(this.hero,l,true)
            RemoveLocation(l)
            l=nil
            this.hero=nil
            this.revive=nil
            this.clock=nil
            this=nil
        end,
       
        create=function(hero)
            local this={}
            this.hero=hero
            this.revive=NewTimer(this)
            TimerStart(this.revive,15.00+5.00*I2R(R2I(SquareRoot(I2R(GetHeroLevel(hero))))),false,Revive.end_revive)
            this.clock=CreateTimerDialog(this.revive)
            TimerDialogSetTitle(this.clock,"You revive in: ")
            if GetLocalPlayer()==GetOwningPlayer(hero) then
                TimerDialogDisplay(this.clock,true)
            end
            return this
        end
    }
   
    --===========================================================================
    function Init_Revive()
        local trigger t=CreateTrigger()
        TriggerRegisterVariableEvent(t,"udg_UnitIndexEvent",EQUAL,2.00)
        TriggerAddCondition(t,Condition(function()
            return IsUnitType(udg_UDexUnits[udg_UDex],UNIT_TYPE_HERO)
        end))
        TriggerAddAction(t,function()
            Revive.destroy(Revive_Instance[udg_UDex])
        end)
        t=nil
        ---- --
        TriggerRegisterAnyUnitEventBJ(gg_trg_Si_mueres_Heroe,EVENT_PLAYER_UNIT_DEATH)
        TriggerAddCondition(gg_trg_Si_mueres_Heroe,Condition(function()
            return IsUnitType(GetDyingUnit(),UNIT_TYPE_HERO)
        end))
        TriggerAddAction(gg_trg_Si_mueres_Heroe,function()
            print("Si")
            Revive_Instance[GetUnitUserData(GetDyingUnit())]=Revive.create(GetDyingUnit())
        end)
        udg_Draeneanos=gg_rct_Region_001
        udg_Demonios=gg_rct_Region_000
    end
end

 

[HerlySQR]

Hello, Is it ok what I did?

 

[Wrda]

Seems like you could knock down several lines if you didn't go OOP and used dynamic functions to its full potential on create function.

 

[HerlySQR]

Seems like you could knock down several lines if you didn't go OOP and used dynamic functions to its full potential on create function.

Eh?

 

[Elprede]

@Wrda While @HerlySQR could combine all the functions into one and drop OOP, he would not be able to easily remove the instance during that UnitIndexEvent.

Well, then again, he could map the timer to the unit.

 

[HerlySQR]

Question, I have to nil all type of variables or is the same in Jass that only that aren't integer, real, boolean, string?

 

[Elprede]

You don't have to set any local variable to nil since there is a garbage collector for it, but don't abuse it.

 

[HerlySQR]

How it works?

 

[HerlySQR]

Question: does "break" interump every loop like that we use in groups or forces and even to check (I mean the filter when we wanna asing a group)?

 

[HerlySQR]

You don't have to set any local variable to nil since there is a garbage collector for it, but don't abuse it.

What do you mean with "don't abuse it"?

 

[Elprede]

Referring to The LUA GC is seemingly disabled, you could create too many objects, such as tables, too fast for the garbage collector to clean up after.

 

[HerlySQR]

I see, is there a way to avoid it?

 

[HerlySQR]

I have a question about the tables, if I wanna clear it I just do?

Table={}
Table[1]=bla
Table["hello"]=bla2
--Clear
Table=nil

Or there is a function to do that?

 

[Eikonium]

If you mean to remove all elements from Table, while still being able to add new elements to it afterwards, you would normally write Table = {}, i.e. set the variable to a fresh new table (and the old table is garbage colleced automatically). Alternatively, you can loop over it and set all keys to nil.

If you mean to remove the table from memory (after you used it for the last time), then you rely on the garbage collector.
The garbage collector only works, if there is no reference left to the table.
That means, if Table is a global variable, yes, it needs to be nilled to make the garbage collector remove it from memory.
If it's used locally (using the local keyword inside any scope block, e.g. a function), then no, you don't need to write Table = nil, as the reference vanishes at the end of the scope block anyway.

Again, I'd like to recommend the same book as I did here.
It contains answers to all questions you ask.

 

[Wrda]

Question: does "break" interump every loop like that we use in groups or forces and even to check (I mean the filter when we wanna asing a group)?

Unfortunately no, only the normal loops "for i =0 do" type of stuff.

 

[HerlySQR]

If you mean to remove all elements from Table, while still being able to add new elements to it afterwards, you would normally write Table = {}, i.e. set the variable to a fresh new table (and the old table is garbage colleced automatically). Alternatively, you can loop over it and set all keys to nil.

If you mean to remove the table from memory (after you used it for the last time), then you rely on the garbage collector.
The garbage collector only works, if there is no reference left to the table.
That means, if Table is a global variable, yes, it needs to be nilled to make the garbage collector remove it from memory.
If it's used locally (using the local keyword inside any scope block, e.g. a function), then no, you don't need to write Table = nil, as the reference vanishes at the end of the scope block anyway.

Again, I'd like to recommend the same book as I did here.
It contains answers to all questions you ask.

I nice know that, and I said I'm not much of read, but I will try, thanks.

Unfortunately no, only the normal loops "for i =0 do" type of stuff.

That's sad.

 

[HerlySQR]

Question: What is faster, still using a unit indexer or use the units as an index?

 

[Eikonium]

using units as index

 

[HerlySQR]

using units as index

Just to be sure, can you prove it?

 

[Uncle]

Just to be sure, can you prove it?

It's definitely faster and easier to work with. The only issue would be desyncs since unit handles are different between clients. See: lua and unit data

 

[HerlySQR]

It's definitely faster and easier to work with. The only issue would be desyncs since unit handles are different between clients. See: lua and unit data

If the problem is for use k,v in pairs; so there is no problem, it is?

 

[Tasyen]

Trokkin did some testing regarding speed of natives vs Lua and shared his results LUA tests and benchmarks .

The trend for the Lua vm is. It is more taxing to communicate with the game then talking with itself.
But one does not change the game when Lua vm just talks with itself. If you code ever shall have any effect onto the game you will need to use a native even if that is slower.

 

[Eikonium]

If the problem is for use k,v in pairs; so there is no problem, it is?

That's right. Using units as an index can only desync, if you iterate over the table via pairs.
If you just use the table to store and read data without iteration, it will not desync.

Also, SyncedTables prevent Desyncs and are safe to iterate, even when you use units as index.

 

[HerlySQR]

That's right. Using units as an index can only desync, if you iterate over the table via pairs.
If you just use the table to store and read data without iteration, it will not desync.

Also, SyncedTables prevent Desyncs and are safe to iterate, even when you use units as index.

Yes, that's why I said there is no problem, because I already use it.