Casting with ‘as’ in C#

Anyone else hate this?

Doofer doofer = GetWidget(widgetId) as Doofer;
Then, somewhere miles away from this innocuous little line, I find that my doofer is unexpectedly null. This is a great way to introduce hard-to-trace bugs, unless of course it’s complimented with guard clauses everywhere to test for nulls, which most of the time means unneccesary clutter.

What’s wrong with good old…

Doofer doofer = (Doofer)GetWidget(widgetId);

In this second case, if the result of GetWidget() can’t be turned into a Doofer, I’ll get an exception thrown right there and then. Assuming that my code here works specifically on doofers, I may as well spit out an exception right up here – how the heck am I supposed to work with this other type of widget you’ve sent me?

I think the only time to use a soft ‘as’ cast is in the tiny minority of cases where you really don’t care if the result of GetWidget can be turned into a Doofer. It seems to me that 90% of the time, you really do care, and you’d like to know as soon as it’s not. Even in that 10%, you’d probably be better off using a null object.

It’s a shame, because the ‘as’ operator is a bit more readable, and we all hate having to slam all those brackets in everywhere. Fortunately, C# provides a little-known solution to this, known as implicit casting.