Programmatic equivalent of default(Type)

Question

I\'m using reflection to loop through a Type\'s properties and set certain types to their default. Now, I could do a switch on the type and set the defau

Answer 1

If you're using .NET 4.0 or above and you want a programmatic version that isn't a codification of rules defined outside of code, you can create an Expression, compile and run it on-the-fly.

The following extension method will take a Type and get the value returned from default(T) through the Default method on the Expression class:

public static T GetDefaultValue()
{
    // We want an Func which returns the default.
    // Create that expression here.
    Expression> e = Expression.Lambda>(
        // The default value, always get what the *code* tells us.
        Expression.Default(typeof(T))
    );

    // Compile and return the value.
    return e.Compile()();
}

public static object GetDefaultValue(this Type type)
{
    // Validate parameters.
    if (type == null) throw new ArgumentNullException("type");

    // We want an Func