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When trying to define a setter that accepts a parameter type that can be used to construct a property, thusly:
class Buffer(buf: String) {}
class Foo {
var buffer: Buffer? = null
set(value: String) {
field = Buffer(value)
}
}
I get the error message:
Setter parameter type must be equal to the type of the property
So what's meant to be the Kotlin way of doing this?
981
Kotlin supports overloading for callables and properties, that is, the ability for several callables (functions or function-like properties) or properties with the same name to coexist in the same scope, with the compiler picking the most suitable one when such entity is referenced.
In Kotlin, setter is used to set the value of any variable and getter is used to get the value. Getters and Setters are auto-generated in the code. Let's define a property 'name', in a class, 'Company'. The data type of 'name' is String and we shall initialize it with some default value.
In Kotlin, getters and setters are optional and are auto-generated if you do not create them in your program.
Properties. Properties are the variables (to be more precise, member variables) that are declared inside a class but outside the method. Kotlin properties can be declared either as mutable using the “var” keyword or as immutable using the “val” keyword. By default, all properties and functions in Kotlin are public.
Kotlin Operator Overloading. Since Kotlin provides user-defined types, it also provides the additional functionality to overload the standard operators, so that working with user-defined types is easier. All of the unary, binary, relational operators can be overloaded. The operators are overloaded either through the member functions or through ...
In Kotlin, setter is used to set the value of any variable and getter is used to get the value. Getters and Setters are auto-generated in the code. Let’s define a property ‘ name ‘, in a class, ‘ Company ‘. The data type of ‘ name ‘ is String and we shall initialize it with some default value. The above code is equivalent to this code:
In order to turn a Kotlin function with a pre-defined name into an operator, we should mark the function with the operator modifier. For example, we can overload the “+” operator: operator fun Point.plus (other: Point) = Point (x + other.x, y + other.y) This way we can add two Points with “+”:
Since Kotlin provides user-defined types, it also provides the additional functionality to overload the standard operators, so that working with user-defined types is easier. All of the unary, binary, relational operators can be overloaded.
As of Kotlin 1.1 it is not possible to overload property setters. The feature request is tracked here:
https://youtrack.jetbrains.com/issue/KT-4075
Currently, you would have to define a buffer extension function on String:
val String.buffer : Buffer
get() = Buffer(this)
and set the value with
Foo().buffer = "123".buffer
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