My $0.02 on internal sealed API vs public virtual discussion

Accidently this post hit the wave of discussion on the blogosphere regarding Microsoft’s approach of keeping very big chunks of APIs internal, sealed, or otherwise unusable by users, and backward compatibility.

To some extent I can agree with both sides, because as always, the truth is in the middle, and I believe we’re talking about the solution (keeping things non-public and non-extensible) instead of the actual problem (the way API is designed, that makes a lot of useless parts public, and useful parts non-visible).

One ridiculous example I saw is the IlGenerator class.

  • It’s public
  • Most of it’s methods are virtual


  • All of it’s constructors are internal

So it’s OK for me to use this class, but I can’t subclass it? Sure it reaches into the guts of the framework, dancing with the devil himself, by manipulating IL stream, but this all looks to me like a carrot on the stick.

From the Good News Department, my colleague Monika started a blog today. She’s a WPF geek, so if you’re into this stuff as well, you should keep an eye on her blog.

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