Coming from (old) Java, curly braces usually meant a scoping construct: method scope or just a simple scope for variables.
In Kotlin, However, They have a more meaningful job as a lambda which is usually helpful. But sometimes it is misleading. Consider the following example:
fun sayHello() = { println("Hello!") }What do you think happens when you call sayHello()?
Just a simple print to the terminal. It’s obvious (at least for me).
Well, think again…
It actually doesn’t do anything except for returning a lambda which will print Hello on invocation.
Just had a similar case in my tests last week:
See if you can spot that error as well. Tests were not running the assertions at all.
And here is the fix:
Using return values and avoiding side effects usually helps to prevent such cases. But is also worth to be just aware of that pitfall.
That’s it for now.
