I've made enough changes to Cog that I'm releasing it as a 2.0 beta. In particular, there are some incompatible changes with the 1.x series. I'd really appreciate if you Cog users out there would download this version and try it out.

The incompatible changes are:

• In 1.4, you could put some generator code on the [[[cog line and some on the ]]] line, to make the generators more compact. Unfortunately, this also made it more difficult to seamlessly embed those markers in source files of all kinds. Code is no longer allowed on the cog marker lines at all.
• In 1.x, you could leave out the [[[end]]] marker, and it would be assumed at the end of the file. Now that behavior must be enabled with a -z switch. Without the switch, omitting the end marker is an error.

Other changes since 1.4:

• The new -d switch removes all the generator code from the output file while running it to generate output (thanks, Blake).
• Cog error messages now print without a traceback, and use a format similar to compiler error messages, so that clicking the message will likely bring you to the spot in your code (thanks, Mike).
• New cog method #1: cog.error(msg) will raise an error and end processing without creating a scary Python traceback (thanks, Alexander).
• New cog method #2: cog.msg(msg) will print the msg to stdout. This is better than print because it allows for all cog output to be managed through Cog.
• The sequence of Cog marker lines is much stricter. This helps to ensure that Cog isn't eating up your precious source code (thanks, Kevin).
• A number of bugs were fixed.

Download the code and let me know what you find.