CodeSOD: Exceptional Standards Compliance

When we're laying out code standards and policies, we are, in many ways, relying on "policing by consent". We are trying to establish standards for behavior among our developers, but we can only do this with their consent. This means our standards have to have clear value, have to be applied fairly and equally. The systems we build to enforce those standards are meant to reduce conflict and de-escalate disagreements, not create them.

But that doesn't mean there won't always be developers who resist following the agreed upon standards. Take, for example, Daniel's co-worker. Their CI process also runs a static analysis step against their C# code, which lets them enforce a variety of coding standards.

One of those standards is: "Catch specific exceptions. Don't catch the generic Exception type unless explicitly necessary." If it is explicitly necessary, their CI system attaches "Comments" (not code comments) to the commit, so all you need to do is click the "resolve" button and provide a brief explanation of why it was necessary.

This wouldn't be an... exceptional standard. Specific is always better than vague, and in this case, the rule isn't hard and fast: you're allowed to violate it if you can explain why.

But explaining yourself sounds like a lot of work. Wouldn't it be easier to try and fool the static analysis tool?

try{ {...}}catch (Exception ex) when (ex is Exception exception){ {...}}

C#'s catch block supports a when operator, which is meant to filter based on properties of the exception. The ex is Exception exception is a pattern match and also a cast: it's true if the type of ex is Exception, and also cast it to Exception and store the cast in exception.

Or to word it another way, we catch the exception if it is of the type Exception but only when the type is Exception in which case we cast the exception which we know is an Exception to Exception and store it in exception, and I take exception to all of that.

Presumably, they'll change the rule in the CI system to exclude these, but hopefully they'll also have a talk with the developer responsible about the purpose of standards. Maybe they'll get some "standards by consent", or maybe somebody'll be looking for a new job.

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