[英]Assigning interface instance to a class that implements that interface
I have various classes that implements IActiveRecord. 我有各种实现IActiveRecord的类。
I want to have a method where I pass in a newly created class and assign ActiveRecord to the type of the class passed in. 我想要一种方法,可以传入新创建的类,然后将ActiveRecord分配给传入的类的类型。
I have tried the below but it does not compile for some reason. 我已经尝试了下面的方法,但是由于某种原因它没有被编译。
Any ideas? 有任何想法吗?
private void AddRecord<T>() where T : class, new()
{
IActiveRecord ActiveRecord = (IActiveRecord)T;
}
Your question is unclear, but if I understand correctly what you are trying to do, you just need to add the constraint where T : IActiveRecord
. 您的问题尚不清楚,但是如果我正确理解您要做什么,则只需
where T : IActiveRecord
添加约束。 Then you can say 那你可以说
void AddRecord<T>() where T : IActiveRecord, new() {
IActiveRecord activeRecord = new T();
// more stuff
}
Regarding your line 关于你的线
IActiveRecord ActiveRecord = (IActiveRecord)T;
this is not legal. 这是不合法的。
T
is a type parameter, not an expression that you can cast. T
是类型参数,而不是您可以强制转换的表达式。
In the method you're displaying, you do not pass in an instance of a certain type ? 在您显示的方法中,您没有传入某种类型的实例吗? I do not really understand what you're trying to achieve.
我不太了解您要达到的目标。
Do you want to do this: 您要这样做吗?
private void AddRecord<T>() where T : IActiveRecord, new()
{
IActiveRecord a = new T();
}
? ?
Looks like you want to constrain the generic type to be of type IActiveRecord
, then you don't need the cast: 看起来您想将泛型类型限制为
IActiveRecord
类型,则不需要IActiveRecord
:
private void AddRecord<T>() where T : IActiveRecord, new()
{
IActiveRecord a = new T();
}
I think you want to restrict your method by using the following: 我认为您想通过使用以下方法来限制您的方法:
private void AddRecord<T>() where T : IActiveRecord, new()
Otherwise, your question might not be clear to me. 否则,我可能不清楚您的问题。
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