Hey all, Today I've seen a lot of messages re: concerns about adding new keywords and breaking backwards compatibility. People have floated a couple approaches to avoiding breakage. But I feel like all of them that I've seen so far will make code confusing. I'd like to propose an alternative, which doesn't perfectly preserve backwards compatibility, but:
1. Allows go 1 and go 2 to be mixed, provided they're in different source files, and 2. Has a clear and trivial upgrade path that can be automated, and can also be done incrementally in a non-disruptive fashion. Here's the idea: the first Go release that includes the new keywords introduces a new specially-recognized comment, something like // go:keywords 2 This comment can be used to control which version of the language source file is interpreted as. So to opt into the new features, a source can add that comment to a source file. At the top. Other source files will continue to treat the new keywords as identifiers. Note that since the keywords are all lower-case, this won't cause problems with interoperability at the API level; any Go 1 package that currently uses one of these keywords as an identifier only does so privately, so Go 2 code can still import those packages and not run into problems with not being able to specify a name in the package. When we finally release "Go 2.0," the only backwards-incompatible change we make is that that the default is to use the new keywords, and we add another specially-recognized comment: // go:keywords 1 which causes the keywords to be treated as identifiers, as in Go 1. We could also add a flag to go build, so that users wanting to build an old Go 1 codebase can just run: go build -go1 And everything will just work. Updating to the new version is easy and can be done incrementally: just rename any variables that collide with the keyword. Thoughts? -Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
