Let's assume a simple class:
class Foo(val p:String)
I would like to create instance of the class by passing lazy delegate:
val lazyP by lazy {"foo"}
println(Foo(lazyP).p)
but I don't need the boilerplate lazyP variable. How to write a one-liner? Something like:
println(Foo(by lazy {"foo"}).p)
I presume what you're trying to do is construct Foo and have p only calculated when it's first called? If so, I don't think that defining Foo as you've done will work, because when you construct Foo, the lazy delegate is called. That's because in order to construct Foo, a string is needed, so the lazy delegate is evaluated at that point. In other words, this:
val lazyP by lazy { "foo" }
val foo = Foo(lazyP)
is more-or-less equivalent to:
val foo = Foo("foo")
I think that if you want Foo to have a lazy delegated property you should define it like this:
class Foo(lazyP: Lazy<String>) {
val p by lazyP
}
Then you can construct it in a one-liner without needing a separate variable:
val foo = Foo(lazy { "foo" })