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by Jiří {x2} Činčura

True and False functions as “oneliners”

29 Jun 2020 1 mins C#

I was reading Stephen Cleary’s A New Pattern for Exception Logging blogpost and the True and False methods caught my eye and I wanted to write them as “oneliners”.

By “oneliner” I mean method that’s using expression body. If you’re looking for answer to “Why?", I don’t have it. So, let’s consider it a quick exercise in C#.

The expression body as the name implies, has to be expression and not bunch of statements in a block. I need to call an Action and return bool. Which is actually Func<bool>. Having that it’s easy to do so.

public static bool False(Action action) => new Func<bool>(() => { action(); return false; })();

You might not like the new being there, luckily casting works just fine.

public static bool False(Action action) => ((Func<bool>)(() => { action(); return false; }))();

Both versions result in same IL, so at the end of the day, it’s only about your personal preference.

And finally, as a little bit of fiddling it can be made bit more obfuscated. Or succinct?

using a = System.Action;
using b = System.Func<bool>;
class C
	const bool f = false;
	public static bool False(a a) => ((b)(() => { a(); return f; }))();

I’ll leave this exercise here, because I feel it could end up with very ugly code.

Profile Picture Jiří Činčura is an independent developer focusing on data and business layers, language constructs, parallelism and databases. Specifically Entity Framework, asynchronous and parallel programming, cloud and Azure. He's Microsoft Most Valuable Professional and you can read his articles, guides, tips and tricks at