[Rd] return (x+1) * 1000

[Mateo Obregón]

I'm not thinking of complicated cases.

This happened to me in a function that returns 10 minute slots

slot <- function (seconds) {
    return (seconds %/% 600) * 600
}

Obviously I found the issue while debugging and corrected my code with 
surrounding parenthesis, but I was surprised that the R parser did not catch 
this syntactic error.

This is especially poignant when we have to switch between languages like 
python where the original line would produce the desired result.

Mateo.
--  
Mateo Obregón.

On Friday, 20 November 2020 21:58:29 GMT Gabriel Becker wrote:
> Hi all,
> 
> I can confirm this occurs for me as well.
> 
> The one thing that comes to mind is that there are certain larger
> expressions that contain calls to return which we absolutely don't want to
> be an error, e.g
> 
> if(somestuff)
>     return(TRUE)
> 
> 
> That said, the actual expression Mateo pointed out certainly does look like
> an error (it definitely isn't going to do what the developer intended).
> 
> I haven't looked at the parser much, to be honest. I assume there is
> perhaps enough differentiation of if/else that return() could be allowed
> within that but not inside a larger expression without it?
> 
> There would be things that are legal (though horrifying) now that would
> stop working though, such as:
> 
> f = function(a) {
> 
>     ret = switch(a,
> 
>                  "1"= return("haha got 1!"),
> 
>                  "2" = "regular ole 2")
> 
>     ret
> 
> }
> 
> 
> Whether it would be a problem or not that such insanity wouldn't work is
> less clear. Are there valid non-if embedded return() cases that are
> important to allow? If so (and if they're not differentiated by the parser,
> which I somewhat doubt switch is, for example, though I'm not certain), I'm
> skeptical we'd be able to do as he suggests.
> 
> It does seem worth considering though. If it can't be a hard parse error
> but we agree many/most cases are problematic, perhaps adding detecting this
> to the static checks that R CMD CHECK performs is another way forward.
> 
> Best,
> ~G
> 
> On Fri, Nov 20, 2020 at 1:34 PM Mateo Obregón <obregonmateo using gmail.com>
> 
> 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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