CODEWITHSUNDEEP
luacoronasdk
Avraam Mavridis
Avraam Mavridis

Reputation: 8920

Calling a function in lua passing a parameter

I have the following function

DOESN'T WORK:

local function onPlayBtnRelease(level)
    storyboard.gotoScene( level, "fade", 500 )
    return true 
end

I want to pass a parameter so the appropriate level to be loaded, so I have the following button:

planet1 = widget.newButton{
    label="1",
        labelColor = { default={255}, over={128} },
        fontSize=25,
        defaultFile="levelplanet.png",
        overFile="levelplanet-over.png",
        width=62, height=62,
        onRelease = onPlayBtnRelease("loadscene1")  -- event listener function
    }

but the above doesn't work.

THAT IS OK:

If I do

local function onPlayBtnRelease
    storyboard.gotoScene( "loadscene1", "fade", 500 )
    return true 
end


planet1 = widget.newButton{
        label="1",
            labelColor = { default={255}, over={128} },
            fontSize=25,
            defaultFile="levelplanet.png",
            overFile="levelplanet-over.png",
            width=62, height=62,
            onRelease = onPlayBtnRelease    
        }

It compiles. How can I pass a parameter to onPlayBtnRelease ? Any idea why this causes a compilation error?

The error:

Runtime error
bad argument #1 to 'find' (string expected, got table)
stack traceback:
        [C]: ?
        [C]: in function 'error'
        ?: in function 'gotoScene'

Upvotes: 1

Views: 3479

Answers (5)

Fazil Mir
Fazil Mir

Reputation: 833

Try this it will work for certain. 

local onPlayBtnRelease = function(event)
    storyboard.gotoScene(event.target.myScene, "fade", 500 )
    return true 
end


planet1 = widget.newButton{
    label="1",
    labelColor = { default={255}, over={128} },
    fontSize=25,
    defaultFile="levelplanet.png",
    overFile="levelplanet-over.png",
    width=62, height=62,
    onRelease = onPlayBtnRelease
}
planet1.myScene = "yourSceneName"

Upvotes: 0

dualed
dualed

Reputation: 10502

Explanation of this line:

onRelease = onPlayBtnRelease("loadscene1")  -- event listener function

This line calls onPlayBtnRelease("loadscene1") and assigns the return value to the field onRelease. So, what you probably need is to do it like this:

onRelease = function() return onPlayBtnRelease("loadscene1") end

If you need to do this a lot, you can make a closure generator like this

local function newclosure(func, ...)
    local args = {...}
    return function()
        return func(unpack(args));
    end
end

This way you only have to write the line like this:

onRelease = newclosure(onPlayBtnRelease, "loadscene1")

Upvotes: 4

EvilAnton
EvilAnton

Reputation: 373

Maybe it is possible to associate needable data outside of the constructor? For example:

planet1 = widget.newButton { -- then initialize as usuall
 }
planet1.next_scene = "loadscene1"

Upvotes: 1

Kamiccolo
Kamiccolo

Reputation: 8497

Wondering, if You can build Widget object with some non-standart options without wrapping it into another table like this:

local function onPlayBtnRelease(event)
    storyboard.gotoScene(event.target.next_scene, "fade", 500 )
    return true 
end


planet1 = widget.newButton{
        label="1",
        labelColor = { default={255}, over={128} },
        fontSize=25,
        defaultFile="levelplanet.png",
        overFile="levelplanet-over.png",
        width=62, height=62,
        next_scene = "loadscene1"
}

If it won't work, table listeners are the ones You're looking for.

Upvotes: 0

LorenzoDonati4Ukraine-OnStrike
LorenzoDonati4Ukraine-OnStrike

Reputation: 6985

The error is most probably caused by:

local function onPlayBtnRelease
    storyboard.gotoScene( "loadscene1", "fade", 500 )
    return true 
end

because of the missing parameter list in the function definition.

The error could be similar to this, I guess:

G:\root\main\core\Lua/app/lua51/bin/lua.exe: lua_08.lua:5: 
 '(' expected near 'storyboard'

From what you posted it seems that onPlayBtnRelease is an event listener function, thus it should be declared as a function taking a single parameter which is the triggered event:

local function onPlayBtnRelease(event)
    // ... code ...
    return true 
end

EDIT

The onRelease field must be the listener, not the result it returns when it is called. Try simply this:

planet1 = widget.newButton{
    label="1",
        labelColor = { default={255}, over={128} },
        fontSize=25,
        defaultFile="levelplanet.png",
        overFile="levelplanet-over.png",
        width=62, height=62,
        onRelease = onPlayBtnRelease
    }

Upvotes: 1

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