On Tue, Mar 21, 2017 at 10:38 AM, Paul Jolly <p...@myitcv.org.uk> wrote: >> The problem was that I repeatedly mentally misread 'indexing' for 'index >> evaluation'. As the index is a constant in this case, it lead me to believe >> it cannot have any effect on the result. But it's the 'indexing', the actual >> time when the value is loaded using the index, which is exempt from the >> 'left-to-right' evaluation rule for operands. > > > I actually read the following part of the spec: > >> Otherwise, when evaluating the operands of an expression, assignment, or >> return statement, all function calls, method calls, and communication >> operations are evaluated in lexical left-to-right order. > > > and inferred "when evaluating the operands of an expression, assignment, or > return statement" every expression that is not a "function call, method call > or communication operation" has an undefined order of evaluation, including > (as the later paragraph clarifies) index expressions. > > Consider for example: > > https://play.golang.org/p/xGaEDjTuzw > > To my understanding, it is undefined when "j-1" evaluates, hence that code > _might_ panic. > > But maybe I read/inferred that incorrectly?
You are correct. The evaluation of `j`--the actual load of the value from the global variable--may take place before or after the call to `foo2`. 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.
