Question

Often, while investigating some code I’m developing, I’ll throw in a Console.WriteLine here or there too see a value when the program is run. The drawback to Console.WriteLine is that I have to wrap an expression in parenthesis and possibly break it apart. For example given this expression:

a().b().c();

let’s suppose I want to print the value of b(). I’ll have to do something like:

var val = a().b();

Console.WriteLine(val);

val.c();

That’s alot of editing just to see a value.

My solution has been to use this extension method:

public static T Disp<T>(this T obj)
{
    Console.WriteLine(obj);
    return obj;
}

I can inject a call to Disp in any method chain without altering the value of the overall expression. To see the result of b() in the above example, I’d do:

a.().b().Disp().c()

My question is, is there already some method like Disp in .NET? Is there a better way to implement Disp? Are there drawbacks to this technique?

update 2012-02-09

I also added an overloaded version which accepts a format string:

public static T Disp<T>(this T obj, string format)
{
    Console.WriteLine(string.Format(format, obj));
    return obj;
}

Answer 1

I don’t see a problem with it, although you might consider making it more general with an Action<T> parameter:

public static T Tap<T>(this T obj, Action<T> act)
{
    act(obj);
    return obj;
}

This is similar to Tap in Ruby.

Instead of your Dump method you can then do:

a.().b().Tap(Console.WriteLine).c()