December Update of the Coding Guidelines for C# 3.0 and C# 4.0

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I finally found some time to update the coding guidelines with some feedback I received since it’s original release in June this year. I’ve removed the following guidelines because I found that they were either very exotic or not general enough for most developers:

  • Avoid side-effects when throwing recoverable exceptions (AV1044)
  • Don’t make assumptions on the object’s state after raising an event (AV1050)
  • Adhere to the LINQ Design Guidelines for custom IQueryable implementations (AV1075)
  • Explicitly define the scope of a type or member (AV1551) because it is a duplicate of AV1501.

I also noticed that the Design Guidelines section is getting bigger with each new version, so I split up that section into three smaller sections. And because of that, I had to renumber the guidelines in the AV1025-1100 range as well. So what about the new guidelines?

Well, these are new ones:

  • Use an interface to support multiple implementations, not a base class (AV1004)
  • Use an interface to decouple classes from each other (AV1005)
  • Avoid bidirectional dependencies (AV1020)
  • Classes should have state and behavior (AV1025)
  • Avoid mutual exclusive properties (AV1110)
  • Don’t expose stateful objects through static members (AV1125)
  • Use exceptions instead of return codes for reporting failures (AV1200)
  • Don’t use nested loops in a method (AV1532)
  • Consider abstracting an external dependency or 3rd party component (AV1580)

As usual, you can download the latest version, its A4 cheat sheet, and Visual Studio 2010 rule sets at

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