CODEWITHSUNDEEP
c#lambda
Joe.wang
Joe.wang

Reputation: 11791

How can view the source code of the lambda expression in the run time(C#)?

All, I am trying to figure out how does lambda expression works in the complied time also in the run time. Say you have the source code like below. enter image description here

Currently, I tried to quick watch the variable. But unfortunately. Can not make it to view the source code of the Fun .Is there any other way to view what does actually code the Func<int> ageCalculator run?. Thanks.

Updated

No lucky things in the reflector kind tools. Please see it in the dotPeek. Thanks.

enter image description here

Updated 1

There are more items (Compiled generated class items) displayed in the tree when the option is enabled. But double-clicked these items. Just display the MyTempClass source code no new thing. What does it suppose to display ? Thanks.

enter image description here

Upvotes: 0

Views: 1141

Answers (4)

Bob Vale
Bob Vale

Reputation: 18474

The key issue is that by returning a Func you return a compiled lambda, you want to return an Expression<Func<int>> instead. You can then call ToString() to see its representation and Compile().Invoke() to run it

Expression<Func<int>> AgeCalculator() {
  int myAge = 30;
  return () => myAge;
}

public void Closure() {
  var ageCalculator = AgeCalculator();
  Console.WriteLine(ageCalculator.ToString());
  Console.WriteLine(ageCalculator.Compile().Invoke());
}

Upvotes: 1

jjchiw
jjchiw

Reputation: 4445

I'm not sure if this it's what you want, but LinqPad has some views Tree, IL that maybe it's what you're looking for....

enter image description here enter image description here

Upvotes: 0

Thomas Weller
Thomas Weller

Reputation: 59303

You can't see the C# source code, because there is none. There's a class generated automatically by the compiler, so the only thing you could see is intermediate code (IL). That IL code might be displayed as C# by other tools like Reflector (I don't have such a tool integrated in Visual Studio, so I can't try).

You can see it in dotPeek when you enable "Show compiler generated code":

dotPeek Setting

Next, right click and choose "Decompiled sources" to show the generated code:

dotPeek Showing the generated class

Upvotes: 1

rickvdbosch
rickvdbosch

Reputation: 15571

I can see some stuff not entirely being used as it is intended to. Please consider the code below:

class Program
{
    static void Main(string[] args)
    {
        // You do not call the method to assign it to the variable, 
        // you point to the method (without parentheses)
        Func<int> answer = GetTheAnswerToEverything;

        // Here you actually call the method
        Console.WriteLine(answer());
        Console.ReadLine();
    }

    // This is the method that you call when you write **add()**
    private static int GetTheAnswerToEverything() => 42;
}

In this example, you actually call the GetTheAnswerToEverything method when you invoke answer().

For more information, see Func Delegate

Encapsulates a method that has no parameters and returns a value of the type specified by the TResult parameter.

Upvotes: 0

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