On Wed, Jul 19, 2017 at 4:10 PM, <adrian.pr...@gmail.com> wrote: > > The EBNF specifies the syntax, not the behavior. EBNF does not indicate the > order of evaluation of source code, only the order of characters in the > source code.
Fair point. In this case it is also intended to indicate the precedence. In fact, in every case I know of, it indicates the precedence. Ian > On Wednesday, July 19, 2017 at 6:59:29 PM UTC-4, Ian Lance Taylor wrote: >> >> On Wed, Jul 19, 2017 at 3:28 PM, <adrian...@gmail.com> wrote: >> > >> > A question on Stack Overflow led me to carefully examine the spec and I >> > feel like there may be some detail that's missing - the behavior is easy >> > enough to work with, but it's effectively undefined according to the >> > language spec. Specifically, with a variable x of type *[]string for >> > example, *x[0] will not work because it is evaluated as *(x[0]), not as >> > (*x)[0]. This is unexpected based on the spec because the only >> > specifications that could apply are the general order of evaluation, which >> > is left to right (not the case here), and operator precedence which states >> > that pointer dereference is a unary operator and unary operators have >> > highest precedence (again clearly not what's happening). >> > >> > The closest it comes to explaining this behavior is in the section on >> > address operators, which implies that the address operator & applies to the >> > entire slice expression next to it (or struct field selector, etc). This >> > leaves one to assume the same implication applies to the pointer >> > dereference >> > operator as well. >> > >> > Is there something covering this that I glossed over reading the spec? >> > If it's not just something I missed, is this worth clarifying in the spec, >> > without changing the behavior (purely a documentation change)? >> >> This is expressed in the EBNF grammar in the language spec. x[0] is a >> PrimaryExpr. *x[0] is a unary_op applied to a PrimaryExpr. >> >> 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. -- 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.
