get modifier of set property

Question

I have a property called MyProperty. I am interested in getting a reference to the object that called the setter of the property. For example:

MyProperty
{
  set
  {
    if (modifer.GetType() == typeof(UIControl))
    {
      //some code
    }
    else
    {
      //some code
    }
  }
}

What is `modifier`, and what is it that you think is the problem with your code? — Guffa, Jun 23 '13 at 21:51
This is where you stop using a property and use a method instead. With an argument. — Hans Passant, Jun 23 '13 at 21:57

score 0 · Answer 1 · answered Jun 23 '13 at 21:51

0

I don't think that's possible unless you unwind the stack? Which you could do but I wouldn't recommend it.

answered Jun 23 '13 at 21:51

Code Junkie

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Interesting, how do you unwind the stack in code? Short of throwing an exception and waiting for a method to return? – Lews Therin Jun 23 '13 at 21:59
@LewsTherin I think he's talking about http://msdn.microsoft.com/library/system.diagnostics.stacktrace.aspx – hangy Jun 23 '13 at 22:01
See bens answer lews... – Code Junkie Jun 23 '13 at 22:49

Snæbjørn · Answer 2 · 2013-06-23T22:13:53.933

0

You could make use of reflection. Though this approach is not something I'd recommend.

StackTrace stackTrace = new StackTrace();
var modifier = stackTrace.GetFrame(1).GetType();

if (modifier == typeof(UIControl))
{
  //some code
}

I didn't test this, but should be about right.

You could also check out CallerMemberNameAttribute, it might be relevant to you.

edited Jun 23 '13 at 22:13

answered Jun 23 '13 at 22:05

Snæbjørn

10,322
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score 0 · Answer 3 · answered Jun 23 '13 at 22:08

It is possible to examine the current stack during run time. This would enable you to check the class of the calling method:

StackTrace stackTrace = new StackTrace();
var callingMethod = stackTrace.GetFrame(1).GetMethod();
var callingType = callingMethod.ReflectedType 
//Or possible callingMethod.DeclaringType, depending on need

However, this type of code should set of alarms. Using reflection to unwind the stack is fragile, unintuitive, and defies separation of concerns. The setter of a property is an abstraction intended to set the value given nothing other than the value to set.

There are several stronger alternatives. Among them, consider having a method called only by UIControls:

public void SetMyPropertyFromUiControl(MyType value)
{
    this.MyProperty = value;
    ... other logic concerning UIControl
}

If the details of the instance of UIControl being used to set the property are important, the method signature might look like:

public void SetMyPropertyFromUiControl(MyType value, UIControl control)
{
    this.MyProperty = value;
    ... other logic concerning UIControl that uses the control parameter
}

The reflecion method will not work if the call to the property was inlined. In this case you can get the caller of your caller method and type back. But it will work perfectly inside the debugger because JIT optimizations are turned off usually while debugging. — Alois Kraus, Jun 23 '13 at 22:15
@AloisKraus Good point! Another reason such an approach is weak. — Ben Reich, Jun 23 '13 at 22:16

score 0 · Answer 4 · edited Jun 23 '13 at 22:16

Actually there is a new feature in .NET 4.5, which is called "Caller Information".

You can get some information about caller like that:

public Employee([CallerMemberName]string sourceMemberName = "", 
                [CallerFilePath]string sourceFilePath = "", 
                [CallerLineNumber]int sourceLineNo = 0)
{
    Debug.WriteLine("Member Name : " + sourceMemberName);
    Debug.WriteLine("File Name : " + sourceFilePath);
    Debug.WriteLine("Line No. : " + sourceLineNo);
}

More information: Caller Info - codeguru.com

get modifier of set property

4 Answers4