Mutator

Why Mutator?

As the immutable object becomes the default pattern of functional programming language, such as Value Object in Java, and Data Class in Kotlin, even the immutable pattern has a lot of advantages, modifying properties of deeply nested immutable objects is still not very convenient, for example:

data classPerson(
valname:String,
valaddress:Address
)
data classAddress(
valnation:Nation,
valstate:String,
valstreet:String
)
data classNation(
valname:String,
valcode:String
)

If we want to modify the Person.address.nation.code, we have to write code like this:

val person =Person(...)
// ...val clone = person.copy(
address = person.address.copy(
nation = person.address.nation.copy(
code ="New Code"
) )
)

Getting Started

1. Add dependency into build.gradle or build.gradle.kts

   dependencies {
   implementation("io.johnsonlee:mutator:1.2.0")
   }

2. Call the extension function mutate(...)

   val clone = person.mutate(Person::address, Address::nation, Nation::code, "New Code")

   The code above is equivalent to the following

   val clone = person.copy(
   address = person.address.copy(
   nation = person.address.nation.copy(
   code ="New Code"
   ) )
   )