[Rd] return (x+1) * 1000

[Henrik Bengtsson]

Without having dug into the details, it could be that one could update
the parser by making a 'return' a keyword and require it to be
followed by a parenthesis that optionally contains an expression
followed by end of statement (newline or semicolon).  Such a
"promotion" of the 'return' statement seems backward compatible and
would end up throwing syntax errors on:

function() return
function() return 2*x
function() return (2*x) + 1

while still accepting:

function() return()
function() return(2*x)
function() return((2*x) + 1)

Just my two Friday cents

/Henrik

On Fri, Nov 20, 2020 at 3:37 PM Dénes Tóth <toth.denes using kogentum.hu> wrote:
>
> Yes, the behaviour of return() is absolutely consistent. I am wondering
> though how many experienced R developers would predict the correct
> return value just by looking at those code snippets.
>
> On 11/21/20 12:33 AM, Gabriel Becker wrote:
> > And the related:
> >
> >     > f = function() stop(return("lol"))
> >
> >     > f()
> >
> >     [1] "lol"
> >
> >
> > I have a feeling all of this is just return() performing correctly
> > though. If there are already R CMD CHECK checks for this kind of thing
> > (I wasnt sure but I'm hearing from others there may be/are) that may be
> > (and/or may need to be) sufficient.
> >
> > ~G
> >
> > On Fri, Nov 20, 2020 at 3:27 PM Dénes Tóth <toth.denes using kogentum.hu
> > <mailto:toth.denes using kogentum.hu>> wrote:
> >
> >     Or even more illustratively:
> >
> >     uneval_after_return <- function(x) {
> >         return(x) * stop("Not evaluated")
> >     }
> >     uneval_after_return(1)
> >     # [1] 1
> >
> >     On 11/20/20 10:12 PM, Mateo Obregón wrote:
> >      > Dear r-developers-
> >      >
> >      > After many years of using and coding in R and other languages, I
> >     came across
> >      > something that I think should be flagged by the parser:
> >      >
> >      > bug <- function (x) {
> >      >       return (x + 1) * 1000
> >      > }
> >      >> bug(1)
> >      > [1] 2
> >      >
> >      > The return() call is not like any other function call that
> >     returns a value to
> >      > the point where it was called from. I think this should
> >     straightforwardly be
> >      > handled in the parser by flagging it as a syntactic error.
> >      >
> >      > Thoughts?
> >      >
> >      > Mateo.
> >      > --
> >      > Mateo Obregón.
> >      >
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> >      >
> >
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