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Great fluent interface sample: the fluent repeater

I'm not that much a fan of fluent interfaces, but in some cases they are well fit.

A great example is the fluent repeater created by Adrian Aisemberg. It's also a good example if you don't know what a fluent interface is.

Here is sample code that uses it:

Repeat.Call<string>(Save).WithParameters("myfile.txt").UntilSucceeds.Start(10);
Repeat.Call(Ping).PauseBetweenCalls(2000).Start(100);

Some more:

Repeat.Call(Open).InBackgroundThread.At(ThreadPriority.Lowest).
        OnSuccessCall(Opened).OnExceptionCall(Failed).Start();

This could be written in the following way using a non fluent interface:

Repeater repeater = new Repeater();
repeater.Method = Open;
repeater.InBackgroundThread = true;
repeater.ThreadPriority = ThreadPriority.Lowest;
repeater.Success += Opened;
repeater.Exception += Failed;
repeater.Start();

Which version do you prefer?

Posted: Apr 24 2008, 03:52 PM by Fabrice Marguerie | with 3 comment(s)
Filed under: , ,

Comments

Matt Kellogg said:

I'm hoping your question is rhetorical. Would someone honestly prefer the non-fluent interface? I think the best thing that's ever happened to fluent interfaces is intellisense.

# April 24, 2008 11:45 AM

Christophe Menet said:

It's not only a matter of "easy writing", but also a matter of "easy reading"!

When I look at your sample, I clearly prefer the non fluent interface, just because I'm use to it. But if you write it this way:

Repeat

 .Call(Open)

 .InBackgroundThread

 .At(ThreadPriority.Lowest)

 .OnSuccessCall(Opened)

 .OnExceptionCall(Failed)

 .Start();

It becomes much more easy to read and to use! For me at least :)

# April 24, 2008 4:17 PM

Fabrice Marguerie said:

This makes it looks as if people are simply after VB's With syntax:

With new Repeater

.Method = Open

.InBackgroundThread = True

.ThreadPriority = ThreadPriority.Lowest

.Success = Opened

.Exception = Failed

.Start()

End With

In the case of the fluent repeater, the order of the invocations isn't important. It's not like a LINQ query where method calls form an ordered chain of operations:

Books

 .Where(book => book.Title.Contains("LINQ")

 .OrderBy(book => book.Price)

 .Select(book => book.Title)

This seems to mean that a fluent interface is superfluous in the case of the repeater.

BTW, is LINQ's API fluent?

# April 24, 2008 5:10 PM
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