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Why does ReSharper tell me “implicitly captured closure”?

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我在风中等你
我在风中等你 2020-12-04 06:20

I have the following code:

public double CalculateDailyProjectPullForceMax(DateTime date, string start = null, string end = null)
{
    Log(\"Calculating Dai
5条回答
  • 慢半拍i
    慢半拍i (楼主)
    2020-12-04 06:48

    Agreed with Peter Mortensen.

    The C# compiler generates only one type that encapsulates all variables for all lambda expressions in a method.

    For example, given the source code:

    public class ValueStore
{
    public Object GetValue()
    {
        return 1;
    }

    public void SetValue(Object obj)
    {
    }
}

public class ImplicitCaptureClosure
{
    public void Captured()
    {
        var x = new object();

        ValueStore store = new ValueStore();
        Action action = () => store.SetValue(x);
        Func f = () => store.GetValue();    //Implicitly capture closure: x
    }
}



    The compiler generates a type looks like :
    


    [CompilerGenerated]
private sealed class c__DisplayClass2
{
  public object x;
  public ValueStore store;

  public c__DisplayClass2()
  {
    base.ctor();
  }

  //Represents the first lambda expression: () => store.SetValue(x)
  public void Capturedb__0()
  {
    this.store.SetValue(this.x);
  }

  //Represents the second lambda expression: () => store.GetValue()
  public object Capturedb__1()
  {
    return this.store.GetValue();
  }
}

    


    And the Capture method is compiled as:
    


    public void Captured()
{
  ImplicitCaptureClosure.c__DisplayClass2 cDisplayClass2 = new ImplicitCaptureClosure.c__DisplayClass2();
  cDisplayClass2.x = new object();
  cDisplayClass2.store = new ValueStore();
  Action action = new Action((object) cDisplayClass2, __methodptr(Capturedb__0));
  Func func = new Func((object) cDisplayClass2, __methodptr(Capturedb__1));
}



    Though the second lambda does not use x, it cannot be garbage collected as x is compiled as a  property of the generated class used in the lambda.
    
    
    
             
    
                                                        
    
            
            
    
              
                
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