See also: https://bugs.r-project.org/bugzilla/show_bug.cgi?id=16710
On Fri, Aug 30, 2019 at 9:02 AM William Dunlap via R-devel <r-devel@r-project.org> wrote: > > Precedence is a property of the parser and has nothing to do with the > semantics assigned to various symbols. Using just core R functions you can > see the precedence of '?' is between those of '=' and '<-'. > > > # '=' has lower precedence than '?' > > str(as.list(parse(text="a ? b = c")[[1]])) > List of 3 > $ : symbol = > $ : language `?`(a, b) > $ : symbol c > > str(as.list(parse(text="a = b ? c")[[1]])) > List of 3 > $ : symbol = > $ : symbol a > $ : language `?`(b, c) > > # '<-' has higher precedence than '?' > > str(as.list(parse(text="a ? b <- c")[[1]])) > List of 3 > $ : symbol ? > $ : symbol a > $ : language b <- c > > str(as.list(parse(text="a <- b ? c")[[1]])) > List of 3 > $ : symbol ? > $ : language a <- b > $ : symbol c > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > > On Fri, Aug 30, 2019 at 4:41 AM Stephen Ellison <s.elli...@lgcgroup.com> > wrote: > > > > From: R-devel [mailto:r-devel-boun...@r-project.org] On Behalf Of Ant F > > > Sent: 29 August 2019 12:06 > > > To: r-devel@r-project.org > > > Subject: [Rd] ?Syntax wrong about `?`'s precedence ? > > > ... > > > See the following example : > > > > > > `?` <- `+` > > > > I'm curious; What did you expect to happen if you replace the function '?' > > with the operator '+' ? > > ? is surely now being evaluated as a user-defined function and not as an > > operator. > > Would you expect the results of doing that to be the same as evaluation > > without replacement? > > > > S Ellison > > > > > > > > > > ******************************************************************* > > This email and any attachments are confidential. Any u...{{dropped:10}} > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
