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Showing posts from February, 2008

DataSets - Love em Hate em

I have a love-hate relationship with DataSets.  On the one hand they are easy to use and contain lots of built in functionality.  On the other hand they are abused by almost everyone but at the same time severely under utilized, meaning that I rarely see anyone use most of the features available. I get the feeling that the majority of developers that use DataSets have blinders on:  DataSets are only useful for reading and writing data to the database.  End of story.  If you are an ASP.NET developer you absolutely refuse to use them and use DataReaders only.  And in the last three years I have not seen too many applications that use the typed DataSets that can be created in Visual Studio 2005. I don't like using DataSets because I prefer to use NHibernate or ActiveRecord to interact with databases.  But lately I have been having a change of heart as I have been delving more and more into using DataSets in the application I am currently working on.  There is a lot of functionality ba

Value Objects as Measurement Objects

So I was reviewing PEAA looking to see if Fowler had come up with the idea of Measurment Objects, that horse I've been kicking around lately.  I found that he has a couple of close patterns:  Value Object and Money. Value Object:  A small simple object, like money or a date range, whose equality isn't based on identity. Money: Represents a monetary value. According to Fowler Value Objects are light weight and almost primative types.  They should also me immutable since they have no identity.  He also suggests that in .NET structs could be used as Value Objects. The money pattern looks like a special case of a Measurement Object with the UnitOfMeasure being set to currency (currency being USD or Euro). I see the usefulness of using structs but there is the boxing issue if we implement them with interfaces. I will have to ponder on this.

Measurement Objects

In my previous post I described setting up a database to track measurements.  I ran into problems quickly with the data model and I could see that it was going to become a convoluted mess pretty quick.  So I want to take a step back and look at it from an application point of view. What I want is a way to track an objects measurements.  I need a system that is easy to understand, any one looking at an object should readily understand what each measurement property is and what units it is in.  The system should accommodate almost any existing system of measurement but at the same time it needs to be simple.  Brain dead simple. What I am thinking is to start out with a abstract base class for our Measurement Object.  It has an ID that can be an int, string or Guid, take your pick.  The Text property is the string representation of the Value, Value being in an abstract class that extends MeasurementBase. I think that it is important to seperate the actual Value into another class of Type