Assign-and-compare in go's while-equivalent?

Question

In Go you can do:

if foo := bar() ; foo != nil {     ... } 

In C/C++ you can do:

while ((foo = bar()) != NULL) {     ... } 

However, Go's syntax does not seem to provide any equivalent way of doing assign-and-compare in a while loop; Go has replaced while with a specific invocation of for (e.g. for a is equivalent to for ; a ;). Simply trying to use the if version syntax confuses the parser, as it's expecting there to be a third statement.

I could just say:

for foo := bar() ; foo != nil ; foo = bar() {     .... } 

but in this case, the bar() call is fairly long, complex, and not easy to break out into its own function (although I could do something like declaring a local func to call, but that still reduces the clarity of the code).

For now I am doing:

for {     foo := bar();     if foo == nil { break; }     ... } 

but this seems unclean, both because it separates the loop criteria from the loop statement itself, and because it relies on break.

So, is there a clean, idiomatic way of doing an assign-and-compare in a while loop in Go? This is such a common use case I can't imagine that there's no way of doing it.

Answer 1

No. Go has no while statement, only the special form of the for statement - and assignment is a statement, not an expression. Your examples are IMHO idiomatic Go.