Building Strings Fluently

Last night I was reading the second edition of Effective C#.  Item 16 discusses avoiding creation of unnecessary objects with part of the discussion using the typical example of favoring StringBuilder over string concatenation.  The tip itself was nothing new, StringBuilder has been available since the first versions of the .NET framework, but it did remind me of something I “discovered” a few months ago.

Back in late July Esther and I took a week vacation.  We rented a two story loft on a marina in southwest Michigan.  It was incredibly relaxing and apparently more refreshing than I realized at the time.  When I returned to the office the following Monday I was looking at a block of code that was doing a lot of string concatenation and decided to rewrite it to use a StringBuilder instead.  When using a StringBuilder I follow the familiar pattern seen in most books and even in the MSDN documentation:

var sb = new StringBuilder();
sb.Append("Hello, Dave");
sb.AppendLine();
sb.AppendFormat("Today is {0:D}", DateTime.Now);
Console.WriteLine(sb.ToString());

For some reason though as I was writing code this particular Monday I noticed something that I hadn’t noticed before.  I realized that StringBuilder, a class I’ve been using for nearly 10 years, implements a fluent interface!  All of those familiar methods like Append, AppendFormat, Insert, Replace, etc… each return the StringBuilder instance meaning we can chain calls together!

Armed with this new knowledge I started thinking about all the places that code can be simplified just by taking advantage of the fluent interface.  No longer do I need to define a variable for the StringBuilder and pass it to something.  Instead, I can create the instance inline, build it up, then pass it along.

Console.WriteLine(
		(new StringBuilder())
		.Append("Hello, Dave")
		.AppendLine()
				.AppendFormat("Today is {0:D}", DateTime.Now)
		.ToString()
);

Hoping I hadn’t been completely oblivious for so long I hopped over to the .NET 1.1 documentation and what I found was astonishing – this functionality has been there all along.  I asked a few trusted colleagues if they knew about it and incredibly none of them had realized it either!  How did we miss this for so long?

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