nested-generics | 易学教程

What do nested generics in C# mean?

阅读更多关于 What do nested generics in C# mean?

问题 A bit of a basic question, but one that seems to stump me, nonetheless. Given a "nested generic": IEnumerable<KeyValuePair<TKey, TValue>> Is this stating that IEnumerable can have generic types that are themselves KeyValuePair 's ? Thanks, Scott 回答1: Yes. The KeyValuePair type expects two generic type parameters. We can either populate them by pointing to concrete types: IEnumerable<KeyValuePair<string, int>> Or we can populate them by using other generic parameters already specified by the

Nested Typescript Generics

阅读更多关于 Nested Typescript Generics

来源： https://stackoverflow.com/questions/51796871/nested-typescript-generics

C# foreach on IEnumerable<IList<object>> compiles but shouldn't

阅读更多关于 C# foreach on IEnumerable compiles but shouldn't

问题 I have the following code: IEnumerable<IList<MyClass>> myData = //...getMyData foreach (MyClass o in myData) { // do something } It compiles, runs and obviously I get an System.InvalidCastException . Why does the compiler not complain? MyClass is a simple bean, no extensions. Edit 1: As suggested by David switching the type from IList to List the compiler complains Edit 2: I've understood that the behaviour is as specified in the C# Language definition. However, I don't understand why such a

Generics C# organization of methods that depends on type [closed]

阅读更多关于 Generics C# organization of methods that depends on type [closed]

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago . I'm Tryng to made a base class with a base method that order a List with a function that depends on Type. My Compiler show this Error Error 13 Impossibile to convert 'System.Linq.Expressions.Expression<System.Func<MLOLPlus.Business.Dealer,string>>' in 'System.Linq.Expressions.Expression<System.Func<T,string>>'.

How to keep generic type of nested generics with class tokens

阅读更多关于 How to keep generic type of nested generics with class tokens

问题 The standard way in Java to work around type erasure is to pass a class token into the constructor. For example we could define a generic property class like this: class Prop<T> { public Prop(Class<T> type) { this.type = type; } Class<T> type; T t; } class IntProp extends Prop<Integer> { public IntProp() { super(Integer.class); } } But what if I now want to use another generic type argument, such as a list and also keep its generics type. I would have liked to do this: class ListProp<J>

Nested Type Parameters in Java

阅读更多关于 Nested Type Parameters in Java

问题 This is an example which I made up to be a simplification of my real code, so I apologize if it is a little contrived. What I would like to do is to effectively get two type parameters out of a single nested type argument. I'm pretty sure this is impossible, but I thought I'd give it a shot. //Not legal java code public class Foo<C extends Collection<T>> { //where T is another type parameter private C coll; public Foo(C coll) { this.coll = coll; } public void add(T elem){ this.coll.add(elem);

Generic tree, self bounded-generics

阅读更多关于 Generic tree, self bounded-generics

问题 I am to adding genericity to one of my projects. I love generics as this makes my code more robust, self-documented and erases all those ugly casts. However, I came across a tough case and have some issues trying to express a "recursive" constraint for one of my structures. This is basically some kind of "generic" tree, with double links (to children and parent). I have simplified the class at maximum to show the issue : public class GenericTree< ParentClass extends GenericTree<?, ?>,

Generic tree, self bounded-generics

阅读更多关于 Generic tree, self bounded-generics

I am to adding genericity to one of my projects. I love generics as this makes my code more robust, self-documented and erases all those ugly casts. However, I came across a tough case and have some issues trying to express a "recursive" constraint for one of my structures. This is basically some kind of "generic" tree, with double links (to children and parent). I have simplified the class at maximum to show the issue : public class GenericTree< ParentClass extends GenericTree<?, ?>, ChildClass extends GenericTree<?, ?>> { // Attributes private ArrayList<ChildClass> children = new ArrayList

Flatten IEnumerable<IEnumerable<>>; understanding generics

阅读更多关于 Flatten IEnumerable; understanding generics

问题 I wrote this extension method (which compiles): public static IEnumerable<J> Flatten<T, J>(this IEnumerable<T> @this) where T : IEnumerable<J> { foreach (T t in @this) foreach (J j in t) yield return j; } The code below causes a compile time error (no suitable method found), why? : IEnumerable<IEnumerable<int>> foo = new int[2][]; var bar = foo.Flatten(); If I implement the extension like below, I get no compile time error: public static IEnumerable<J> Flatten<J>(this IEnumerable<IEnumerable

C# foreach on IEnumerable<IList<object>> compiles but shouldn't

阅读更多关于 C# foreach on IEnumerable compiles but shouldn't

I have the following code: IEnumerable<IList<MyClass>> myData = //...getMyData foreach (MyClass o in myData) { // do something } It compiles, runs and obviously I get an System.InvalidCastException . Why does the compiler not complain? MyClass is a simple bean, no extensions. Edit 1: As suggested by David switching the type from IList to List the compiler complains Edit 2: I've understood that the behaviour is as specified in the C# Language definition . However, I don't understand why such a cast/conversion is allowed, since at runtime I always get an InvalidCastException. I opened this in