将DataContext传递到Action() [英] Passing DataContext into Action()

问题描述

代替:

 using(MyDataContext db = new MyDataContext())
 {
   //do something
 }

我想使用一个Action()

I'd like to use an Action()

public static class SimpleUsing
{
  public static void DoUsing(Action action)
  {
    using(MyDataContext db = new MyDataContext())
    {
      //do something
    }
  }
}

将用作

SimpleUsing.DoUsing(() =>
{
   //but how to get DataContext variable?
}

主要问题是如何访问"db"变量以利用DataContext?

The main issue is how do I access the "db" variable to make use of the DataContext?

推荐答案

通用类型Action<T1>，Action<T1, T2>等定义了一个接受一些参数的委托.所以你可以这样写:

The generic types Action<T1>, Action<T1, T2>, etc. define a delegate which takes some arguments. So you can write it like this:

public static class SimpleUsing
{
    public static void DoUsing(Action<MyDataContext> action)
    {
        using (MyDataContext db = new MyDataContext())
           action(db);
    }

    public static T DoUsing(Func<MyDataContext, T> fn)
    {
        using (MyDataContext db = new MyDataContext())
           return fn(db);
    }
}

// ...

SimpleUsing.DoUsing(db => {
    // do whatever with db
});

var result = SimpleUsing.DoUsing(db => {
    return 42; // uses Func overload, result will be 42
});

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