Creating an immutable value object in C# - Part II - Making the class better

Luca Bolognese's WebLog : Creating an immutable value object in C# - Part I - Using a class

Thu, 06 Dec 2007 20:37:22 GMT

PingBack from http://blogs.msdn.com/lucabol/archive/2007/12/03/creating-an-immutable-value-object-in-c-part-i-using-a-class.aspx

re: Creating an immutable value object in C# - Part II - Making the class better

Tom Kirby-Green — Fri, 07 Dec 2007 15:30:56 GMT

This is shaping up to be a very timely and useful mini series Luca :-) Please don't keep us waiting too long for the next part!

re: Creating an immutable value object in C# - Part II - Making the class better

Marcelo Cantos — Fri, 21 Dec 2007 10:46:29 GMT

First off, the most practical representation of date spans is an inclusive lower bound and exclusive upper bound, i.e., [start, end). Equally important, they should be treated as points in time (which is what DateTime represents), not complete days. Thus, new DateTime(d, d) is empty for any d (solving empty ranges) and new DateTime(d, d.AddDays(1)) is exactly one day.

Also, the type should really be DateTimeSpan.

Convenience properties such as a static DateSpan.Empty would come in handy.

Finally, DateTime has MaxValue and MinValue, which serve as fairly natural surrogates for +/- infinity, and also eliminate edge-cases from set operations.

re: Creating an immutable value object in C# - Part II - Making the class better

Marcelo Cantos — Fri, 21 Dec 2007 10:48:05 GMT

Oops! Wherever I said 'new DateTime', I meant 'new DateSpan'.

re: Creating an immutable value object in C# - Part II - Making the class better

lucabol — Fri, 21 Dec 2007 20:36:35 GMT

Thanks for the comment. It makes me think of something an old functional guy said once: "The idea of reusing objects across domain boundaries is absurd, not even something as simple as Person can be defined the same way in different domains".

In my domain (a stock backtesting app) a DateSpan needs to have a day boundary, not a point in time boundary. Also, inclusive lower and upper bounds have been working pretty well for my app so far (even if I can see that your definition has conceptual appeal).

And anyhow, I'm just trying to show how to use some language features. I don't care much about the particular sample. I could have chosen Complex, but I thought it was too boring ...

Creating an immutable value object in C# - Part III - Using a struct

Luca Bolognese's WebLog — Tue, 25 Dec 2007 01:39:25 GMT

Other posts: Part I - Using a class Part II - Making the class better In Part II I talked about the asymmetry

Creating an immutable value object in C# - Part III - Using a struct

Noticias externas — Tue, 25 Dec 2007 02:01:25 GMT

Other posts: Part I - Using a class Part II - Making the class better In Part II I talked about the asymmetry

Creating an immutable value object in C# - Part IV - A class with a special value

Luca Bolognese's WebLog — Sat, 29 Dec 2007 02:45:33 GMT

Other posts: Part I - Using a class Part II - Making the class better Part III - Using a struct In the

Creating an immutable value object in C# - Part IV - A class with a special value

Noticias externas — Sat, 29 Dec 2007 03:06:20 GMT

Other posts: Part I - Using a class Part II - Making the class better Part III - Using a struct In the

re: Creating an immutable value object in C# - Part II - Making the class better

kfarmer@microsoft.com — Sat, 29 Dec 2007 08:54:21 GMT

Luca: Consider...

public DateTime Start { get; private set; }

re: Creating an immutable value object in C# - Part II - Making the class better

lucabol — Sun, 30 Dec 2007 02:15:50 GMT

Hey Kit,

Automatic properties don't prevent setting the property from inside the class. The readonly keyword does.

Creating an immutable value object in C# - Part V - Using a library

Luca Bolognese's WebLog — Fri, 11 Jan 2008 21:36:12 GMT

Other posts: Part I - Using a class Part II - Making the class better Part III - Using a struct Part

Creating an immutable value object in C# - Part V - Using a library

Noticias externas — Fri, 11 Jan 2008 21:52:05 GMT

Other posts: Part I - Using a class Part II - Making the class better Part III - Using a struct Part

Immutability in C#

Thu, 17 Jan 2008 02:36:53 GMT

For some reason, there's been a lot of buzz lately around immutability in C#. If you're interested in

The Quest for Quick-and-Easy Class-Based Immutable Value Objects in C# - Part 1: Introduction

adamjcooper.com/blog — Tue, 03 Jun 2008 22:37:59 GMT

The Quest for Quick-and-Easy Class-Based Immutable Value Objects in C# - Part 1: Introduction

The Quest for Quick-and-Easy Immutable Value Objects in C#

adamjcooper.com/blog — Tue, 03 Jun 2008 23:57:34 GMT

The Quest for Quick-and-Easy Immutable Value Objects in C#