Hi, I am Amit Shekhar, Co-Founder @ Outcome School • IIT 2010-14 • I have taught and mentored many developers, and their efforts landed them high-paying tech jobs, helped many tech companies in solving their unique problems, and created many open-source libraries being used by top companies. I am passionate about sharing knowledge through open-source, blogs, and videos.
Before we start, I would like to mention that, I have released a video playlist to help you crack the Android Interview: Check out Android Interview Questions and Answers.
In this blog, we will learn about the noinline
modifier in Kotlin.
This article was originally published at Outcome School.
What is a noinline
in Kotlin?
Assume that we do not want all of the lambdas passed to an inline
function to be inlined, in that case, we can mark those function parameters with the noinline
modifier.
As we are learning about the noinline
, we must be knowing about the inline
keyword in Kotlin. You can learn here.
Let's understand this noinline
modifier with an example.
fun guide() {
print("guide start")
teach({
print("teach abc")
}, {
print("teach xyz")
})
print("guide end")
}
inline fun teach(abc: () -> Unit, xyz: () -> Unit) {
abc()
xyz()
}
Let's go to the decompiled code. The decompiled code is as below:
public void guide() {
System.out.print("guide start");
System.out.print("teach abc");
System.out.print("teach xyz");
System.out.print("guide end");
}
Here, both the lambdas(abc
, xyz
) passed to an inline function got inlined.
What if we want only the first lambda(abc
) to get inlined but not the second lambda(xyz
)?
In that case, we will have to use the noinline
modifier with that lambda(xyz
).
Our updated code:
fun guide() {
print("guide start")
teach({
print("teach abc")
}, {
print("teach xyz")
})
print("guide end")
}
inline fun teach(abc: () -> Unit, noinline xyz: () -> Unit) {
abc()
xyz()
}
Again, let's go to the decompiled code. The decompiled code is as below:
public void guide() {
System.out.print("guide start");
System.out.print("teach abc");
teach(new Function() {
@Override
public void invoke() {
System.out.print("teach xyz");
}
});
System.out.print("guide end");
}
public void teach(Function xyz) {
xyz.invoke();
}
Here, we can see that the lambda(xyz
) has not got inlined as expected. Only the lambda(abc
) got inlined. This is how noinline
in Kotlin helped us in achieving what we wanted.
This way, we used the noinline
to avoid the inlining.
Now, we have understood the noinline
in Kotlin.
Learn about crossinline: crossinline in Kotlin
Master Kotlin Coroutines from here: Mastering Kotlin Coroutines
That's it for now.
Thanks
Amit Shekhar
Co-Founder @ Outcome School
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