C# && DotNet Tips - The DebuggerDisplay() attribute

October 09, 2017 | #code

Debugging is one of the most crucial skills that a software developer can possess. I want to share a tip I recently learned while watching a great Pluralsight course. When debugging your C# code, wouldn't it be nice to know some interesting data about the giant collection of objects you are hovering over? That is where the DebuggerDisplay() attribute steps in!

To quote the excellent MSDN docs:

Debugger display attributes allow the developer of the type, who specifies and best understands the runtime behavior of that type, to also specify what that type will look like when it is displayed in a debugger.

How to use the DebuggerDisplay() attribute

Let's assume we have a simple Person class who is not using the DebuggerDisplay functionality.

public class PersonWithoutDebuggerDisplay
{
    public string Name { get; set; }
    public int AgeInYears { get; set; }

    public PersonWithoutDebuggerDisplay(string name, int years)
    {
        Name = name;
        AgeInYears = years;
    }
}
  1. Add using statement for System.Diagnostics.
  2. Decorate your class or property with the [DebuggerDisplay("")] attribute. Inside the quotation marks you can write your own custom message which will override the default message, which simply displays either your types information or the ToString() override if one is present.

For example: 

[DebuggerDisplay("This person is named {Name} and is {AgeInYears} old")]
public class PersonWithoutDebuggerDisplay
{
    public string Name { get; set; }
    public int AgeInYears { get; set; }

    public PersonWithoutDebuggerDisplay(string name, int years)
    {
        Name = name;
        AgeInYears = years;
    }
}

The debugger display showing our custom message

To me, this could definitely help save me some extra clicks and would be helpful when working with a large collection of complex data.

Considerations

  • There will be overhead for this operation
  • If we name our properties well, we shouldn't need to use this

What are your thoughts on the DebuggerDisplayAttribute?

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