[英]Using inherited types with C# collection generic type parameters
我有一個抽象類,其中有一些繼承類,例如:
internal abstract class SomeBaseType {}
internal class FirstSpecificType : SomeBaseType {}
internal class SecondSpecificType : SomeBaseType {}
internal class ThirdSpecificType : SomeBaseType {}
以及具有受約束的通用類型參數的類:
internal class SomeCollection<T> : ICollection<SomeDataStructure>
where T : SomeBaseType {}
我創建了一個List<SomeCollection<SomeBaseType>>
並嘗試添加各種繼承類的元素SomeBaseType
但我得到以下錯誤( CS1503和CS1950 ):
Argument 1: cannot convert from 'Namespace.SomeCollection<FirstSpecificType>' to 'Namespace.SomeCollection<SomeBaseType>'
The best overloaded Add method 'List<SomeCollection<SomeBaseType>>.Add(SomeCollection<SomeBaseType>)' for the collection initializer has some invalid arguments
由於FirstSpecificType
是SomeBaseType
,我應該能夠做到,對吧? 這基本上與向IList<object>
添加任意object
集相同。
對於其他上下文,出現此錯誤的代碼如下所示:
protected Constructor()
{
collectionOne = new SomeCollection<FirstSpecificType>();
collectionTwo = new SomeCollection<SecondSpecificType>();
collectionThree = new SomeCollection<ThirdSpecificType>();
allCollections = new List<SomeCollection<SomeBaseType>>
{
// Each of these three collections has the error
collectionOne,
collectionTwo,
collectionThree
};
}
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