接口中的 C# 构造函数
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C# constructor in interface
提问by Toto
I know that you can't have a constructor in an interface, but here is what I want to do:
我知道接口中不能有构造函数，但这是我想要做的：
interface ISomething
{
void FillWithDataRow(DataRow)
}
class FooClass<T> where T : ISomething , new()
{
void BarMethod(DataRow row)
{
T t = new T()
t.FillWithDataRow(row);
}
}
I would really like to replace ISomething's FillWithDataRowmethod with a constructor somehow.
我真的很想以某种方式用构造函数替换ISomething'sFillWithDataRow方法。
That way, my member class could implement the interface and still be readonly (it can't with the FillWithDataRowmethod).
这样，我的成员类可以实现接口并且仍然是只读的（它不能使用FillWithDataRow方法）。
Does anyone have a pattern that will do what I want?
有没有人有一种模式可以做我想做的事？
采纳答案by Jon Skeet
(I should have checked first, but I'm tired - this is mostly a duplicate.)
（我应该先检查一下，但我累了 - 这主要是重复的。）
Either have a factory interface, or pass a Func<DataRow, T>into your constructor. (They're mostly equivalent, really. The interface is probably better for Dependency Injection whereas the delegate is less fussy.)
要么有一个工厂接口，要么将 a 传递给Func<DataRow, T>您的构造函数。（它们几乎是等效的，真的。接口可能更适合依赖注入，而委托则不那么挑剔。）
For example:
例如：
interface ISomething
{
// Normal stuff - I assume you still need the interface
}
class Something : ISomething
{
internal Something(DataRow row)
{
// ...
}
}
class FooClass<T> where T : ISomething , new()
{
private readonly Func<DataRow, T> factory;
internal FooClass(Func<DataRow, T> factory)
{
this.factory = factory;
}
void BarMethod(DataRow row)
{
T t = factory(row);
}
}
...
FooClass<Something> x = new FooClass<Something>(row => new Something(row));
回答by NDM
use an abstract class instead?
改用抽象类？
you can also have your abstract class implement an interface if you want...
如果你愿意，你也可以让你的抽象类实现一个接口......
interface IFillable<T> {
void FillWith(T);
}
abstract class FooClass : IFillable<DataRow> {
public void FooClass(DataRow row){
FillWith(row);
}
protected void FillWith(DataRow row);
}
