I find the code very useful. I've checked the Core Foundation sources numerous times when I wanted to know how something was implemented. Apple's documentation

I find the code very useful. I've checked the Core Foundation sources numerous times when I wanted to know how something was implemented. Apple's documentation is sometimes lacking, and it's great when you run into a problem and you can just read the sources. Unfortunately, CF is always released pretty late (it's "coming soon" for months), and it would be nice if much more was Open Source. But I'm happy about every bit of code that's public!