proposal: Go 2: extend "continue" to jump to start of function

[jfcg]

continue statement begins the next iteration of the innermost "for" loop at its post statement. The "for" loop must be within the same function. If there is a label, it must be that of an enclosing "for" statement, and that is the one whose execution advances.

In addition to the above officially specified definition of continue keyword, I am proposing to extend its definition to also include the containing function body as the outer-most layer. That means:

• "continue" goes to the start of the containing function if there is no enclosing for loop
• "continue functionName" goes to the start of the containing function

I occasionally find myself using for {} or labels/gotos for an entire function, so I thought this would be a harmless and useful addition to Go. What do you think?

Note: When examining this, I realized we can create labels inside functions with the same name. So you can have a label main: inside main(). So I think it would be better to forbid such label names inside a function if this proposal is accepted.

Note 2: Since we have return, we don't need to change anything about "break".

[ianlancetaylor]

Within a loop, continue has a vaguely sensible meaning: continue with the next iteration of the loop. I can't see any way that continue implies that we should jump to start of the current function. A function is not a loop.

It also doesn't seem like something that comes up all that often. In https://blog.golang.org/go2-here-we-come Robert outlined three criteria for language changes. I'm not sure this meets criteria 1: address an important issue for many people.

[beoran]

As you noted, this can already be done using goto and a label. However, I would say that it's better in most cases to refactor the function and split the loop body into a separate function, that returns whether or not a continue is needed as a boolean.

[mdaliyan]

"continue functionName" makes no sense. What you say is some kind of "repeat functionName" that makes no sense either. You can just run your function recursively or use labels.

[bradfitz]

This doesn't seem to have much, if any, support, so this looks like it'll be a likely decline.

Leaving open for four more weeks for final comments, though.

[ianlancetaylor]

No final comments.