Kotlin Extensions property vs. function - Conflict

Question

I have the two following definitions.

The first one as an extension function allowing to set visible a View and also to set it as gone or invisible with the second parameter.

fun View.setVisible(visible: Boolean, goneWhenVisibleFalse: Boolean) {
    visibility = when {
        visible -> View.VISIBLE
        goneWhenVisibleFalse -> View.GONE
        else -> View.INVISIBLE
    }
}

The second here, as an extension property using the first above.

var View.visible: Boolean
    get() = visibility == View.VISIBLE
    set(value) {
        setVisible(value, true)
    }

None of complicated until here. The code compiles and the app launch correctly. BUT I get a black screen, no error in the logcat, nothing to get a trace.

After a while, I change the signature of the first function to receive the second parameter with true as default:

fun View.setVisible(visible: Boolean, goneWhenVisibleFalse: Boolean= true)

And then it works normally. The question is: why this happen? I dug into the bytecode. But looks there is no duplication of signatures, the number of parameters is different in both cases.

Maybe a bug of kotlin? I'm using kotlin plugin v1.2.30

working fine with me in v1.2.31, with no default value for the parameter — y.allam, Apr 04 '18 at 15:51
kinda strange code bacause setVisible(value, true) will be always GONE — Andrey Danilov, Apr 04 '18 at 15:53
It's impossible to answer "why did it happen?" without being able to debug your actual app. We're not aware of any bugs in Kotlin that manifest themselves as users' apps hanging with no diagnostics. — yole, Apr 04 '18 at 16:11
@yole, yes you are right. but the code is simple. you can try your own implementation. I was looking for comments to better understand this behavior. — crgarridos, Apr 04 '18 at 16:21
@DEADMC @user221256 ok, let say the extension property is named `gone`, the issue is the same — crgarridos, Apr 04 '18 at 18:01

score 0 · Answer 1 · edited Apr 04 '18 at 17:25

0

Use this:

View.setVisible(visible: Boolean, goneWhenInvisible: Boolean = false) { 
    visibility = if (visible) View.VISIBLE 
    else if (goneWhenInvisible) View.GONE 
    else View.INVISIBLE
}

edited Apr 04 '18 at 17:25

crgarridos

8,758
3
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answered Apr 04 '18 at 16:13

user221256

415
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Yes, also with **= true**. But why without any of them? – crgarridos Apr 04 '18 at 16:37
@crgarridos I don't understand can you explain it more, please? – user221256 Apr 05 '18 at 17:48

Kotlin Extensions property vs. function - Conflict

1 Answers1