[英]c# Abstract Generic Class inheriting from Abstract Generic Class
I'm trying to create an abstract generic class which inherits from another abstract generic class. 我正在尝试创建一个继承自另一个抽象泛型类的抽象泛型类。
Here's what I have so far 这是我到目前为止的
public abstract class BaseClass {
public long Id { get; private set; }
public BaseClass(long id) {
this.Id = id;
}
}
public abstract class BaseClass<T> : BaseClass where T : BaseClass {
protected BaseClass(long id)
: base(id) {
}
public static T Get(long id) {
T item;
return TryGet(id, out item) ? item : default(T);
}
public static bool TryGet(long id, out T item) {
item = null; // This is where I call the cache but for this example I've removed so it will compile
if (item != null) { return true; }
else {
// Call TryGetFallback method
return false;
}
}
protected abstract T TryGetFallback(long id);
}
public abstract class DerivedClass : BaseClass<DerivedClass> {
public String Name { get; private set; }
public DerivedClass(long id, String name)
: base(id) {
this.Name = name;
}
}
public class DerivedDerivedClass : DerivedClass {
protected override DerivedDerivedClass TryGetFallback(long id) {
// Handle the try get fallback
}
}
The TryGetFallback method on the DerivedDerivedClass causes a compiler error. DerivedDerivedClass上的TryGetFallback方法导致编译器错误。
First you need to fix your BaseClass<T>
implementation to not have a recursive type constraint. 首先,您需要修复
BaseClass<T>
实现,使其不具有递归类型约束。
public abstract class BaseClass<T> : BaseClass where T : new() {
//snip
}
Then you can use it in your derived class, for example I will make it use int
for the generic type parameter: 然后,您可以在派生类中使用它,例如,我将使
int
用于泛型类型参数:
public abstract class DerivedClass : BaseClass<int> {
//snip
}
And now if you compile it will warn you that 'DerivedDerivedClass' does not implement inherited abstract member 'BaseClass<int>.TryGetFallback(long)'
现在,如果您进行编译,它将警告您
'DerivedDerivedClass' does not implement inherited abstract member 'BaseClass<int>.TryGetFallback(long)'
Thanks for the tips @DavidG it's helped me to solve the problem with the following code 感谢@DavidG的提示,它通过以下代码帮助我解决了问题
public abstract class BaseClass {
public long Id { get; private set; }
public BaseClass(long id) {
this.Id = id;
}
}
public abstract class BaseClass<T> : BaseClass where T : BaseClass<T>, new() {
protected BaseClass(long id) : base(id) { }
public static T Get(long id) {
T item;
return TryGet(id, out item) ? item : default(T);
}
public static bool TryGet(long id, out T item) {
item = null; // Try to get item from cache here
if (item != null) { return true; }
else {
T obj = new T();
item = obj.TryGetFallback(id);
return item != null;
}
}
protected abstract T TryGetFallback(long id);
}
public abstract class DerivedClass<T> : BaseClass<T> where T : DerivedClass<T>, new() {
public String Name { get; private set; }
public DerivedClass() : base(0) { }
public DerivedClass(long id, String name)
: base(id) {
this.Name = name;
}
protected abstract override T TryGetFallback(long id);
}
public class DerivedDerivedClass : DerivedClass<DerivedDerivedClass> {
public DerivedDerivedClass() {
}
protected override DerivedDerivedClass TryGetFallback(long id) {
throw new NotImplementedException();
}
}
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