In certain corners of the PHP meta-programming world, it's become fashionable to use PHPDoc comments as a mechanism for providing semantically meaningful information to a program. That is, other code will parse the doc blocks and do something significant with the information encoded in those comments. 

[Doctrine's annotations](http://docs.doctrine-project.org/projects/doctrine-common/en/latest/reference/annotations.html) and code generation are an example of this. 

What's the earliest (or some early) use of this technique? I have vague memories of some early java *Design by Contract* implementations doing similar things, but I'm not sure of those folks were inventing the technique, or if they got it from somewhere. 

Mainly asking so I can provide some historical context for PHP developers who haven't come across the technique before, and are distrustful of it because it seems a little crazy pants.