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Fluent Interfaces Fnar

I really don't get all the excitement about Fluent Interfaces.

Glenn pointed to a post on Fluent Refactoring. He takes some code that looks like this:

Owner owner = GetAccountOwner();
Lookup to = new Lookup(EntityName.queue, Settings.Default.ControlQueueID);
Lookup from = new Lookup(EntityName.systemuser, owner.Value);
Guid regarding = PostState.new_parentpolicy.Value;
Picklist priority = PickLists.EmailPriority.Type.High;
SendMail(from, to, title, body, owner, regarding, priority);

And refactors the api to look like this:

Owner owner = GetAccountOwner(); // not sure why this line is here
.From(EntityName.systemuser, owner.Value)
.To(EntityName.queue, Settings.Default.ControlQueueID)

I'm sure they have a place but people just seem to see opportunity for a fluent interface everywhere they look at the moment. I also have a problem with the readability of some fluent interfaces. For example, does the .Title method change a property on the Priority object or does it change the base e-mail? Intuitively, because I understand e-mails it's more likely to be the latter but it isn't totally clear.

I figure your Email object would have to have properties as well so why go to the trouble of mapping all this to a fluent interface? What's wrong with doing it the OO way? Have I missed something fundamental here?

Mail mail = new Mail();

mail.Owner = GetAccountOwner();
mail.From = new Lookup(EntityName.queue, Settings.Default.ControlQueueID);
mail.To = new Lookup(EntityName.systemuser, owner.Value);
mail.Regarding = PostState.new_parentpolicy.Value;
mail.Priority = PickLists.EmailPriority.Type.High;
mail.Title = title;
mail.Body = body;


Better still, you could make sure you take any mandatory parameters in the constuctor so you're guaranteed to have an object in a valid state (as we discussed in this post: Initialisation using constructors).


Josh Post By Josh Twist
1:23 AM
24 Sep 2007

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Posted by Inferis @ 24 Sep 2007 2:16 AM
It sort of reminds me of the mess TurboVision was. Not exactly the same, but I didn't like it anyway.

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