Untitled.kt

# announcements

[sbyrne]

Untitled.kt

Untitled.kt

[Andreas Sinz]

This sounds like a XY problem, what are you trying to achieve?

[Egor Trutenko]

lazy in Kotlin is just a wrapper around underlying type, so basically if you want your variable to be lazy, it needs to be Lazy<String>. by keyword just delegates get function to something else (in this case - to Lazy instance, which is acquired by calling by readWriteLazy....

[sbyrne]

I'm trying to work around a bug in a 3rd party library that has a by lazy var that does something horribly inefficient, and I want to replace the var.

[Andreas Sinz]

You can't replace the var as it is, all you can do is work around it e.g. add an extension-function and use that instead of the property

[Andreas Sinz]

where does readWriteLazy come from?

[russhwolf]

try var foo by readWriteLazy { "b" }

[sbyrne]

I just realized that readWriteLazy is not part of stdlib. It is internal fun <T> readWriteLazy(initializer: () -> T): ReadWriteProperty<Any?, T> = ReadWriteLazyVal(initializer)

[sbyrne]

Which goes down a rabbit hole of other stuff defined in this library.

[sbyrne]

I fixed the underlying issues, so I no longer want to do this.

[sbyrne]

Although out of curiosity, I guess I still have the same question. Why can't I replace the lazy initializer on a var after initialization?

[Egor Trutenko]

@sbyrne I answered earlier. Because function readWriteLazy returns wrapper around the value, which abstracts over access to this value, making it lazy. by keyword just delegates access to this wrapper, leaving the value intact

[Andreas Sinz]

@sbyrne I guess they left it out because you could change how the internals of a class works and thus get surprising behaviors afterwards