Recent questions tagged generics

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generics - A peculiar feature of exception type inference in Java 8

While writing code for another answer on this site I came across this peculiarity: static void testSneaky() { ... They seem very much alike. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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817 views

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generics - Accessing a property of derived class from the base class in C#

In C#, what is the best way to access a property of the derived class when the generic list contains just the ... from the derived classes } } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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930 views

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generics - Java- The meaning of <T extends Comparable<T>>?

The full context being: public class RClass<T extends Comparable<T>> Would I be right in saying that the ... Comparable OR one of its derived classes? Thanks. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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generics - Are there strongly-typed collections in Objective-C?

I'm new to Mac/iPhone programming and Objective-C. In C# and Java we have "generics", collection classes ... Does a similar mechanism exist in Objective-C? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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generics - The trait cannot be made into an object

I have the following code: extern crate futures; // 0.1.24 use futures::Future; use std::io; struct ... there are other ways to implement the same behavior? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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719 views

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generics - How to determine if a List is sorted in Java?

I would like a method that takes a List<T> where T implements Comparable and returns true or false depending on ... to check if the list is in reverse order. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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856 views

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generics - Java Class.cast() vs. cast operator

Having being taught during my C++ days about evils of the C-style cast operator I was pleased at first to ... operator as a language construct similar to C++? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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generics - Passing dynamic object to C# method changes return type

I created a class that inherits DynamicObject and want to create a static method that can create new ... actually just Visual Studio 2013 getting confused? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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806 views

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generics - How does the reified keyword in Kotlin work?

I'm trying to understand the purpose of the reified keyword, apparently it's allowing us to do reflection ... to explain when this makes an actual difference? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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732 views

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generics - How do I store a value of type Class<ClassImplementingProtocol> in a Dictionary of type [String:Class<Protocol>] in Swift?

I want to store a more specialized type in a Dictionary of type [String:SomeClass]. Here is some sample code ... Thing without a type parameter doesn't work. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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768 views

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generics - Java: Array of primitive data types does not autobox

I have a method like this: public static <T> boolean isMemberOf(T item, T[] set) { for (T t : set) { if ... [], but that doesn't seem to happen. Any insights? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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913 views

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generics - Why can't the C# constructor infer type?

Why is type inference not supported for constructors the way it is for generic methods? public class MyType<T ... the constructor can't support type inference? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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847 views

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generics - Java Enum definition

I thought I understood Java generics pretty well, but then I came across the following in java.lang.Enum: ... where a similar type parameter could be used. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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713 views

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generics - Reflection type inference on Java 8 Lambdas

I was experimenting with the new Lambdas in Java 8, and I am looking for a way to use reflection on the lambda ... out composed return types } } return null; } Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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841 views

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generics - Java 1.6: Creating an array of List<T>

Why can't I create an array of List ? List<String>[] nav = new List<String>[] { new ArrayList<String>() ... compiles... Seems pretty simple, why won't it work? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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879 views

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generics - Is it possible to add type constraints to a Swift protocol conformance extension?

I would like extend Array to add conformance to a new protocol - but only for arrays whose elements themselves ... compiles as given in the original question. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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973 views

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generics - Java type inference: reference is ambiguous in Java 8, but not Java 7

Lets say we have 2 classes. An empty class Base, and a subclass of this class Derived. public class Base { ... How could <T extends Base> ever match Collection? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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735 views

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generics - How do I write the lifetimes for references in a type constraint when one of them is a local reference?

I have a trait Matrix and generic function semi_def<T: Matrix>(x: &T) that I would like to operate on that trait. The ... .transpose() * x 32 | | } | |_^ Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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940 views

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generics - In TypeScript, how to get the keys of an object type whose values are of a given type?

I've been trying to create a type that consists of the keys of type T whose values are strings. In ... Link to a code sample in the TypeScript playground Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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932 views

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generics - Java map with values limited by key's type parameter

Is there a way in Java to have a map where the type parameter of a value is tied to the type parameter of ... , even if it means using some slightly ugly casts. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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700 views

1 answer

generics - What is a higher kinded type in Scala?

You can find the following on the web: Higher kinded type == type constructor? class AClass[T]{... ... as type parameter, therefore the question above. Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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818 views

1 answer

generics - What is SuppressWarnings ("unchecked") in Java?

Sometime when looking through code, I see many methods specify an annotation: @SuppressWarnings("unchecked") What does this mean? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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646 views

1 answer

generics - Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?

Following on from this question, can someone explain the following in Scala: class Slot[+T] (var some: T) { // DOES NOT ... : class Slot[+T] (val some: T) { } Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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891 views

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generics - What does <T> (angle brackets) mean in Java?

I am currently studying Java and have recently been stumped by angle brackets(<>). What exactly do they mean? public ... that I can create an object of type T? Question&Answers:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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784 views

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generics - Difference between <? super T> and <? extends T> in Java

This question already has answers here: Question&Answers:os...

asked Oct 16, 2021 in Technique[技术] by 深蓝 (71.8m points)

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749 views

1 answer

generics - What is the point of the diamond operator (<>) in Java?

The diamond operator in java 7 allows code like the following: List<String> list = new LinkedList<>(); ... feature? Is my understanding of this concept flawed? Question&Answers:os...

asked Oct 16, 2021 in Technique[技术] by 深蓝 (71.8m points)

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948 views

1 answer

generics - Kotlin: generate a Factory by class

We're trying to do some generic processing in kotlin. Basically, for a given class, we want to get the ... //stackoverflow.com/questions/65849484/kotlin-generate-a-factory-by-class...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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769 views

1 answer

generics - How to implement decorator in Rust?

I am learning Rust and I am stuck with a toy example. I have already read documentation on lifetimes, ... /stackoverflow.com/questions/65864390/how-to-implement-decorator-in-rust...

asked Oct 7, 2021 in Technique[技术] by 深蓝 (71.8m points)

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