Friday, August 18, 2017

Tuples in C#7

One of the nice features in C#7 is the support for Tuples as a lightweight datastructure using the System.ValueTuple NuGet package. It simplifies your codebase where you had to fallback before to out parameters or arbitrary objects.

Let’s have a look at a simple example:

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This sample shows how easy it is to return tuples from your methods. Only problem I have with this implementation is that if you try to access the output of this method call, you still see the Item1, Item2 properties which are not really meaningful:

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You don’t have to stop there, we can update the method signature with some extra metadata:

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If we now try to access the tuple values again, we see the following instead:

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NOTE: The name associated with the tuple element is not a runtime metadata, i.e. there is no such a property/field with the name on the actual instance of that value tuple object, the property names are still Item1, Item2, etc., all element names are design time and compiler time only. If we decompile the code with JustDecompile, we see the following:

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Notice the attribute generated on top of the code. This TupleElementNames attribute is picked up by Visual Studio and the compiler and provides the necessary intellisense. This guarantees that it also works when you import this DLL into another project…

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