spot7.org logo
Home PHP C# C++ Android Java Javascript Python IOS SQL HTML Categories

How to define a trait with methods accepting any subtype of a particular trait


Try this


trait AppModel {}
trait ModelOperations {
  def get[T<:AppModel](model: T): Option[T]
  def create[T<:AppModel](model: T): Boolean
}

class User extends AppModel { val id = "xyz" val name = "abc" }

class UserOperations extends ModelOperations { override def get[User](user: User) : Option[User] = { // get a new user object by filtering existing parameters return None } override def create[User](user: User): Boolean = { // do something return false } }


Categories : Scala

Related to : How to define a trait with methods accepting any subtype of a particular trait
Iterative as a trait with Traversable
The problem is not with using Traits, but because you are implementing the wrong interface. See this note on the manual page for Traversable: This is an internal engine interface which cannot be implemented in PHP scripts. Either IteratorAggregate or Iterator must be used instead. Write class BasicIterator implements Iterator instead, since that is the interface whose methods you have inclu

Categories : PHP
Store value in struct through trait
The problem is, as the error message says, that the trait TraitToImpl is not object safe. That is, it is not safe to use that particular trait through a reference (i.e. &TraitToImpl or Box<TraitToImpl>. Specifically, the dosomethn method takes self by value. Consider: how does the compiler call this method on a Cont that's been placed in a Box<TraitToImpl>? It has to copy the v

Categories : Rust
Rust error trait weird method missing
You must add the following line either at the top of the source file or inside main to bring the Error trait's method in scope: use std::error::Error; You can now also call the trait method as if it was a static function, which doesn't require adding the above line: fn main() { let e = O; println!("Hello, world!{}", error::Error::description(&e)) }

Categories : Rust
Copying ArrayList to same and subtype ArrayLists?
In your second for loop you have: for (int i = 1; i < orderProcessor.size(); i++){ computerPart.add((ComputerPart) orderProcessor.get(I)); } If orderProcessor only had 1 order in it, then it would never get added to your coumputerPart arrayList because i would not be less than orderProcessor.size(). You can also check the types of your sub classes to add them into the correct ArrayList. Lik

Categories : Java
IsAlpha function not accepting my input
That's because letter[SIZE] is considered as a pointer pointing to the first element of your array. So your while(!isalpha(letter[SIZE])) is only checking if the first character is alphanumeric or not. Here's an example for a better understanding; Try and print letter[SIZE] on the screen. int main() { const int SIZE = 10; char letter[SIZE]; cout << "Enter a word. "; cin >> letter

Categories : C++
Recently Add
head :: tail pattern matching for strings
What is the easiest and most efficient way to make a min heap in Scala?
Removing mutable collections and making it look more scala style
Reverse list of n elements
scalac: Error: object CharRef in intelliJ 14
Scala - trouble with type inference in lambda expression
Exception on spark test
How can I emulate Haskell's typeclasses in Scala?
Slick: CRUD extension: How to encapsulate implicit mapping:BaseColumnType[T]
Can't find Traverse for sequencing Seq[ValidationNel[String, MyCaseClass]] => ValidationNel[String, Seq[MyCaseClass]]
Tail recursion: internal "loop" function or default values for accumulators
Scala - Add element:MyType to Array = option[MyType] expected
Scala, Composing Function with two values
Using dependent type to generate compile error
How to match all words in a sentence with scala combinators?
Parser Alternative Operator | Fails
ScalaTest assertion mismatch due to Physical Address
Scala implicit parameter and japanese smiley 'foldLeft'
Is it possible to user reduceByKey((x, y, z) => ...)?
How to implement security Authorization using scala and play?
SSO login using scala script
Sum elements based on a predicate
Keep track of completed Futures
API Observable with dynamic caching
java.io.IOException: Remotely closed in gatling
Scala permutations using two lists
Is Scala Either really a Monad
Spark: Use of distinct
Identifying two type wildcards as identical
how to package spark scala application
© Copyright 2017 spot7.org Publishing Limited. All rights reserved.