Thanks to visit codestin.com
Credit goes to github.com

Skip to content

Improve the "Backwards compatible case classes" guide with Scala 2 and 3 specifics #2788

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 3 commits into
base: main
Choose a base branch
from
Draft

Improve the "Backwards compatible case classes" guide with Scala 2 and 3 specifics #2788

Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
dccd24e
Improve the "Backwards comptaible case classes" guide with Scala 2 an…
sideeffffect May 3, 2023
80939c8
Add `apply` methods
sideeffffect May 3, 2023
d6c5b3d
Remove mentions of `copy` for Scala 2
sideeffffect May 5, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Add apply methods
  • Loading branch information
@sideeffffect
sideeffffect committed May 3, 2023
commit 80939c85b30f43fcbe527d3583dd760798af42bb
8 changes: 6 additions & 2 deletions _overviews/tutorials/binary-compatibility-for-library-authors.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -263,7 +263,7 @@ alice match

Later in time, you can amend the original case class definition to, say, add an optional `address` field. You
* add a new field `address` and a custom `withAddress` method,
* update the public `apply` method in the companion object to initialize all the fields,
* add a new `apply` method to the companion object to initialize all the fields and adjust the old `apply`,
* tell MiMa to [ignore](https://github.com/lightbend/mima#filtering-binary-incompatibilities) changes to the class constructor. This step is necessary because MiMa does not yet ignore changes in private class constructor signatures (see [#738](https://github.com/lightbend/mima/issues/738)).
* (Scala 2) add the new field to the `copy` method
* (Scala 3) add a new case to the `fromProduct` method in the companion object
Expand All @@ -274,14 +274,16 @@ Later in time, you can amend the original case class definition to, say, add an
case class Person private (name: String, age: Int, address: Option[String]) {
...
// Add the new field to the `copy` method
private def copy(name: String = name, age: Int = age, address: Option[String] = None) = new Person(name, age, address)
private def copy(name: String = name, age: Int = age, address: Option[String] = address) = new Person(name, age, address)
// Add the `withXxx` method
def withAddress(address: Option[String]) = copy(address = address)
}

object Person {
// Update the public constructor to also initialize the address field
def apply(name: String, age: Int): Person = new Person(name, age, None)
// Add a new `apply` with the address field
def apply(name: String, age: Int, address: Option[String]): Person = new Person(name, age, address)
}
~~~
{% endtab %}
Expand All @@ -294,6 +296,8 @@ case class Person private (name: String, age: Int, address: Option[String]):
object Person:
// Update the public constructor to also initialize the address field
def apply(name: String, age: Int): Person = new Person(name, age, None)
// Add a new `apply` with the address field
def apply(name: String, age: Int, address: Option[String]): Person = new Person(name, age, address)
// Add a new case to `fromProduct`
def fromProduct(p: Product): Person = p.productArity match
case 2 =>
Expand Down