generics Questions

3

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I need a linked node to hold some different interface types, so I made it with generics, but the generics type any can't be compared to nil, it shows error as in the comment: package main type myI...
Davidadavidde asked 8/10, 2022 at 20:14

3

This is a question that I wondered about since the lambdas had been introduced in Java, and inspired by a related question, I thought that I might bring it up here, to see whether there are any ide...
Napiform asked 31/3, 2016 at 14:51

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Is it possible to merge the props of two generic object types? I have a function similar to this: function foo<A extends object, B extends object>(a: A, b: B) { return Object.assign({}, a, ...
Mississippian asked 5/4, 2018 at 22:37

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I just want to know for what java.util.Collections.checkedList() is actually used. I have some code that I know is returning me a List<String> but it's being passed through a chain of messa...
Pili asked 21/7, 2009 at 19:17

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I read the following code in "Java - The beginner's guide" interface SomeTest <T> { boolean test(T n, T m); } class MyClass { static <T> boolean myGenMeth(T x, T y) { boo...
Saddlery asked 6/7, 2015 at 11:50

2

I have: struct Plumbus<'a> { grumbo: &'a dyn Grumbo, } trait Grumbo { fn dinglebop<T>(&self, x: &mut T) -> bool { false } } but I get: error[E0038]: the trait `Grumbo...
Reber asked 21/4, 2018 at 5:18

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Given a constructor public MyObject(int id){ ID = id; } And two enums: public enum MyEnum1{ Something = 1, Anotherthing = 2 } public enum MyEnum2{ Dodo = 1, Moustache= 2 } Is it possibl...
Risarise asked 8/9, 2016 at 13:26

1

I have an existential type defined like this: trait Collection { type Element; } impl<T> Collection for Vec<T> { type Element = T; } type Existential<T> = impl Collection<E...
Calque asked 24/4, 2019 at 9:25

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I know this question has been asked often but I'm unable to find a solution. How can I get a generic type class name in a Spring injected repository? Here it is my base repository public interfa...
Suave asked 12/5, 2015 at 22:15

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.NET 7 recently introduced IParsable as an interface, and I'd like to check for its presence. Some test that will return true if T implements IParsable<T> and false otherwise. Say I want to r...
Pinnatiped asked 19/11, 2022 at 17:6

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Is there a way with C# generics to limit a type T to be castable from another type? Example: Lets say I am saving information in the registry as a string, and when I restore the information I would...
Avictor asked 24/7, 2013 at 6:46

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Why do I get compiler errors with this Java code? 1 public List<? extends Foo> getFoos() 2 { 3 List<? extends Foo> foos = new ArrayList<? extends Foo>(); 4 foos.add(new SubFoo())...
Shaped asked 6/10, 2008 at 22:22

4

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Why cant I use an IEnumerable with params? Will this ever be fixed? I really wish they would rewrite the old libraries to use generics...
Clinic asked 24/1, 2010 at 20:49

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EDIT: I changed a bit the example for getting the idea: Like <Integer or Float> ...without having to create a common interface and make a subclass for Integer and Float to implement it ...
Rhymester asked 24/7, 2012 at 14:42

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I'm trying to use a Class<?> in an if statement, like the following: public static Model get(Class<? extends FooBase> type, long id ) { switch (type) { case FooType.class: return n...
Ran asked 4/3, 2014 at 23:52

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I have a class A and a class B extends A In another class C I have a field private List<B> listB; Now, for some unusual reason, I have to implement this method in C public List<A> ...
Acker asked 7/7, 2010 at 13:14

2

Please take a look at my code: Object longL = 2548214; Map<String, Object> map = new HashMap<String, Object>(1); map.put("LongNumber", longL); List<Map<String, Object>> re...
Joline asked 17/3, 2019 at 7:56

0

I have missed a problem with the Java Generic type public class MyTest { @Test public void test1() throws Exception { List<Integer> list = getMapInstance(); } public static <T extend...
Conk asked 11/5 at 8:13

5

How can I make a generic template type argument required? So far, the only way I found to do it is using never but it causes an error to happen at a different place other than the callsite of the ...
Ingressive asked 1/11, 2018 at 21:50

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In this tutorial on reflection it states: [...] because generics are implemented via type erasure which removes all information regarding generic types during compilation My knowledge was tha...
Dorothydorp asked 8/10, 2013 at 16:23

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I have this scenario: class A<T> I want a constrain of type Person like class A<T> where T: Person and I want A to inherit from B too. example: class A<T> : B : where T:...
Yearning asked 8/4, 2014 at 14:33

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I'm trying to create a generic version of a NamedTuple, as follows: T1 = TypeVar("T1") T2 = TypeVar("T2") class Group(NamedTuple, Generic[T1, T2]): key: T1 group: List[T2] g = Group(1, [""]) #...
Economic asked 25/5, 2018 at 14:2

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If I have a class: class Spaceship<FuelType> { function prepareForLiftoff() throws { //Start the countdown! } } I originally assumed that I would be able to override prepareForLiftoff w...
Rubbico asked 23/11, 2015 at 1:24

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I want to create a class that can store objects conforming to a certain protocol. The objects should be stored in a typed array. According to the Swift documentation protocols can be used as types:...
Lungi asked 22/7, 2014 at 13:21

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I have a class like that: public class Wrapper<T> { private String message; private T data; public String getMessage() { return message; } public void setMessage(String message) { ...
Disentwine asked 13/11, 2011 at 1:27

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