covariance

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Covariance and Contravariance inference in C# 4.0

When we define our interfaces in C# 4.0, we are allowed to mark each of the generic parameters as in or out. If we try to set a generic parameter as out and that\'d lead to a problem, the compiler rai[详细]

2022-12-28 18:12 分类：问答
Using Covariance with an Interface Base Type in .NET 4?

I have some entities created with LINQ-to-SQL. Six of these entities (representing values primarily in drop-down lists) implement an interface I\'ve called IValue. I did this because the UI layer is g[详细]

2022-12-28 04:01 分类：问答
How to accomplish covariant return types when returning a shared_ptr?

using namespace boost; class A {}; class B : public A {}; class X { virtual shared_ptr<A> foo(); }; class Y : public X {[详细]

2022-12-27 22:43 分类：问答
Does C# 4's covariance support nesting of generics?

I don\'t understand why \'x\' below converts, but \'y\' and \'z\' do not. var li开发者_如何学Pythonst = new List<List<int>>();[详细]

2022-12-27 21:30 分类：问答
Covariance and contravariance real world example

I\'m having a little trouble understanding how I would use covariance and contravariance in the real world.[详细]

2022-12-27 20:00 分类：问答
Using Sub-Types And Return Types in Scala to Process a Generic Object Into a Specific One

I think this is about covariance but I\'m weak on the topic... I have a generic Event class used for things like database persistance, let\'s say like this:[详细]

2022-12-27 17:14 分类：问答
java generics covariance

I am having trouble understanding the following article: http://www.ibm.com/developerworks/java/library/j-jtp01255.html[详细]

2022-12-27 01:31 分类：问答
Is there a way to achieve covariance of generic types in C# 3.0?

This has been introduced in C# 4.0, but is there a way to achieve this in c# 3.0? For e.g., consider the following code:[详细]

2022-12-25 12:10 分类：问答
Generics : List<? extends Animal> is same as List<Animal>?

I am just trying to understand the 开发者_JAVA技巧extends keyword in Java Generics. List<? extends Animal> means we can stuff any object in the List which IS A Animal[详细]

2022-12-25 09:11 分类：问答
Why does C# (4.0) not allow co- and contravariance in generic class types?

What is the real reason for that limitation? Is it just work that had to be done? Is it conceptually hard? Is it impossible?[详细]

2022-12-24 08:12 分类：问答