Kotlin Extension Methods Potential Pitfall: Extensions are Resolved Statically
Example
The extension method to be called is determined at compile-time based on the reference-type of the variable being accessed. It doesn't matter what the variable's type is at runtime, the same extension method will always be called.
open class Super
class Sub : Super()
fun Super.myExtension() = "Defined for Super"
fun Sub.myExtension() = "Defined for Sub"
fun callMyExtension(myVar: Super) {
println(myVar.myExtension())
}
callMyExtension(Sub())
The above example will print "Defined for Super", because the declared type of the variable myVar is Super.
