generics

问题 Considering there is a method static IEnumerable<IComparable> q() { return new List<string>(); } I am trying to achieve the same but on my own classes and as a result i receive casting error cs0266 I tried to cast this way return (Common<Message>)new A(); but it results InvalidCastException interface Common<T> where T : Message { T Source { get; } void Show(); } interface Message { string Message { get; } } class AMsg : Message { public string Message => "A"; } class A : Common<AMsg> { public

问题 Considering there is a method static IEnumerable<IComparable> q() { return new List<string>(); } I am trying to achieve the same but on my own classes and as a result i receive casting error cs0266 I tried to cast this way return (Common<Message>)new A(); but it results InvalidCastException interface Common<T> where T : Message { T Source { get; } void Show(); } interface Message { string Message { get; } } class AMsg : Message { public string Message => "A"; } class A : Common<AMsg> { public

问题 So I'm getting the "This construct causes code to be less generic than indicated by the type annotations. The type variable 'a has been constrained to be type 'CountType'." warning, and the constraint is causing a problem in other bits of the code. I've tried making the type explicitly generic, but it's not working. I've put this code on tryfsharp to make it easier to play with. Apologies for the mound of code, I tried cutting it down and simplifying some types. module Stuff type CountType =

问题 So I'm getting the "This construct causes code to be less generic than indicated by the type annotations. The type variable 'a has been constrained to be type 'CountType'." warning, and the constraint is causing a problem in other bits of the code. I've tried making the type explicitly generic, but it's not working. I've put this code on tryfsharp to make it easier to play with. Apologies for the mound of code, I tried cutting it down and simplifying some types. module Stuff type CountType =

问题 So I'm getting the "This construct causes code to be less generic than indicated by the type annotations. The type variable 'a has been constrained to be type 'CountType'." warning, and the constraint is causing a problem in other bits of the code. I've tried making the type explicitly generic, but it's not working. I've put this code on tryfsharp to make it easier to play with. Apologies for the mound of code, I tried cutting it down and simplifying some types. module Stuff type CountType =

问题 Let's say I have the following classes Animal , Fish , and CatFish . CatFish extends Fish and Fish extends Animal . There is a generic class called MyPets , which has a type parameter (generic) called T , and that will be parameterized with the above classes' objects. My question is, how do I create a lower bounded method in D that will take any objects that is a PARENT class of the CatFish class. 回答1: You can't. TL;DR: Type parameters can have several bounds, like in class Box {...} . But a

问题 Let's say I have the following classes Animal , Fish , and CatFish . CatFish extends Fish and Fish extends Animal . There is a generic class called MyPets , which has a type parameter (generic) called T , and that will be parameterized with the above classes' objects. My question is, how do I create a lower bounded method in D that will take any objects that is a PARENT class of the CatFish class. 回答1: You can't. TL;DR: Type parameters can have several bounds, like in class Box {...} . But a

问题 I am trying to build my own Form builder. It was going well until the point when I wanted to get a Value from a Cell . I wanted to make it generic as possible, for instance some Cell s could be responsible of ValueType of Int and others could be String . Anyways, my all Cell s basically conforms to protocol called BaseCell . I assigned a associatedType to this protocol and added a variable value which would return different types for each Cell . After some tryings I come with with the

问题 This question already has answers here : Java generics type erasure: when and what happens? (7 answers) Closed 4 years ago . There two programs Why is the first code code working?I expected it to throw a Run time Exception while accessing the elements as String is added instead of Integer Similarly.. The second code is throwing Run time Exception while accessing the element though it is able to add Integer in the arrayList comfortably despite declaring it to hold String. In both the codes,We

问题 This question already has answers here : Java generics type erasure: when and what happens? (7 answers) Closed 4 years ago . There two programs Why is the first code code working?I expected it to throw a Run time Exception while accessing the elements as String is added instead of Integer Similarly.. The second code is throwing Run time Exception while accessing the element though it is able to add Integer in the arrayList comfortably despite declaring it to hold String. In both the codes,We