c＃generics cast from和to derived [英] c# generics casting from and to derived

问题描述

我有以下类组

类RowBase {int a; }

类历史< T> ：列表< T>其中T：RowBase {int b; }

类SymbolRow：RowBase {int c;}

class SymbolHistory：History< SymbolRow> {

符号S;

}

我需要转换此作业

历史< RowBase> cache = new SymbolHistory（）;

解决方案

这不是一个新问题。互联网上有很多关于它的讨论，例如https://stackoverflow.com/questions/3528821/generics-and-casting-cannot-cast-inherited-class-to-base-class。

I have the following class group

class RowBase { int a; }

class History<T> : List<T> where T: RowBase { int b; }

class SymbolRow : RowBase { int c;}

class SymbolHistory : History<SymbolRow>{

Symbol S;

}

I need to cast this assignment

History<RowBase> cache = new SymbolHistory();

解决方案

It is not a new problem. There are a lot of discussions about it on the Internet, for example, here https://stackoverflow.com/questions/3528821/generics-and-casting-cannot-cast-inherited-class-to-base-class .

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