Hello, World! I'm finding myself doing this a lot...

# announcements

[bod]

Hello, World! I'm finding myself doing this a lot (especially with enums):

val isStateXyz = xx.state in setOf(FOO, BAR, FOOBAR)

Is this idiomatic? Also, I think it may be a bit bad performance...

So I was thinking of creating this:

inline fun Any?.equalsAny(vararg objects: Any?): Boolean = objects.any { this == it }

and use it like this val isStateXyz = xx.equalsAny(FOO, BAR, FOOBAR)

Is it a good idea or should I just keep using in? Thoughts?

[araqnid]

imho the only problem with in setOf(..) is recreating the set each time. But in general I use in with EnumSet a lot, and then it’s just a bitmask check

[Mikael Alfredsson]

for the setof case, i assume that you only have a finite number of setof to test against, so initialize those inside the enum and create helpermethods that returns booleans.

[bod]

@araqnid are you saying you do i in EnumSet.of( ... ?

[araqnid]

I try to cache the sets I want to check against in companion objects etc, so it’s that I do in someSet where someSet is an EnumSet

[bod]

allright

[bod]

well...... I guess I'll just keep in then

[bod]

thanks for your input, all :)

[araqnid]

yes, if the sets are static, then extension properties on the enum would look good val SomeEnum.isStateXyz get() = this in xyzStates

[araqnid]

oh hey, I just discovered you can define extension properties as delegates:

operator fun <T : Enum<T>> EnumSet<T>.getValue(owner: T, property: KProperty<*>): Boolean {
            return owner in this
        }

so then you can define:

val SomeEnum.isStateXyz by EnumSet.of(FOO, BAR, FOOBAR)

[araqnid]

Today I Learned 🎉

[bod]

wow, beautiful 🙂