covariant Questions
1
I've been recently learning Kotlin, while having some questions with covariant type.
The sample code is here.
I have Option and Option2 both having a type parameter T and a run extension.
I coul...
Kopans asked 19/4, 2019 at 16:50
2
For example I have a Processor base class with a method that returns an Object and takes Object as a parameter. I want to extend it and create a StringProcessor which will return String and take St...
2
Solved
This code:
comboBoxMonth.Items.AddRange(UsageRptConstsAndUtils.months.ToArray());
public static List<String> months = new List<String>
{
"Jan",
"Feb",
"Mar",
"Apr",
"May",
...
Biggin asked 5/11, 2015 at 22:1
3
Solved
I'm trying to implement a Clonable class with the CRTP. However, I need to have abstract class that have a pure virtual clone method, overridden by child classes. To make this happen, I need the cl...
Predetermine asked 15/5, 2015 at 5:22
1
Solved
I've been told by several people that Java allows covariant array subtyping in other words if A is a subtype of B, then A[] is a subtype of B[], but that this is a bad feature because it can lead t...
Intent asked 17/2, 2015 at 20:51
7
I get a compile error when I try to do this:
class A
{
virtual std::vector<A*> test() { /* do something */ };
}
class B: public A
{
virtual std::vector<B*> test() { /* do something ...
Tragedy asked 12/9, 2014 at 17:10
3
Solved
While reading on Covariant Overriding, i find out very strange fact,
covariant method overriding is implemented using a bridging technique.
it also said that this feature is implemented in java...
Eurypterid asked 6/9, 2013 at 10:24
6
I have the following structure:
public interface BarReturn {}
public interface FooReturn {}
public interface FooBarReturn extends FooReturn, BarReturn {}
public interface Foo {
FooReturn fooBar...
3
Solved
The following C++ code gives me these errors when compiled:
covariant.cpp:32:22: error: invalid covariant return type for ‘virtual Q<B> C::test()’
covariant.cpp:22:22: error: overriding ‘vir...
3
Why does below code prints "1" ?
class A {
int x = 1;
}
class B extends A {
int x = 2;
}
class Base {
A getObject() {
System.out.println("Base");
return new B();
}
}
public class Covaria...
4
A virtual function's return type should be the same type that is in base class, or covariant. But why do we have this restriction?
Anatomize asked 28/1, 2011 at 8:47
1
Solved
I know in Java arrays are covariant. So for example:
Assume Dog is a subclass of Animal
In java the arrays are covariant making: Animal[] a supertype of Dog[]
But in java generic collections are ...
3
Solved
I have a subclass that needs to return a subclass of the return type of its parent class. I believe this is called a covariant return type. I am wondering the simplest way to convert from the paren...
3
Solved
I'm trying to understand this but I didn't get any appropriate results from searching.
In C# 4, I can do
public interface IFoo<out T>
{
}
How is this different from
public interface IFo...
2
Solved
Since Java 5 we are allowed to have covariant return types. Why doesn't the Java API take advantage of this?
Take Graphics2D.create() for instance. Why isn't it overridden to return a Graphics2D o...
Ala asked 20/9, 2010 at 11:48
1
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