R devel - Sep 2020 - sys.call() 's srcref doesn't match the language

Dear R-devel,

I found this behavior disturbing, if `1 + f()` is called, `sys.call()`
called inside of `f` will return a quoted `f()` with a "srcref" that
prints
"1 + f()".

I don't know which one is good but I don't think they can be correct at
the
same time.

Here's a reproducible example:

f <- function(){
  sc <- sys.call()
  print(sc)
  attr(sc, "srcref") <- NULL
  print(sc)
  1
}
f2 <- function() {
  1 + f()
}
f()
#> f()
#> f()
#> [1] 1
f2()
#> 1 + f()
#> f()
#> [1] 2

Best,

Antoine

	[[alternative HTML version deleted]]

Hello,

The source references are useful for debugging tools because they
allow linking to call sites in the source files.

I agree the output can be confusing. Perhaps this could be fixed by
tweaking the print method for calls. If the deparsed call doesn't
match the srcref, both could be displayed along with file:line:column.

```
#> f()
#> <srcref:file.R:2:3>
#> 1 + f()
```

Best,
Lionel


On 9/2/20, Antoine Fabri <antoine.fabri at gmail.com>
wrote:
> Dear R-devel,
>
> I found this behavior disturbing, if `1 + f()` is called, `sys.call()`
> called inside of `f` will return a quoted `f()` with a "srcref"
that prints
> "1 + f()".
>
> I don't know which one is good but I don't think they can be
correct at the
> same time.
>
> Here's a reproducible example:
>
> f <- function(){
>   sc <- sys.call()
>   print(sc)
>   attr(sc, "srcref") <- NULL
>   print(sc)
>   1
> }
> f2 <- function() {
>   1 + f()
> }
> f()
> #> f()
> #> f()
> #> [1] 1
> f2()
> #> 1 + f()
> #> f()
> #> [1] 2
>
> Best,
>
> Antoine
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

Thanks Lionel,

I now understand what's going on. I like your proposal and I can confirm I
wouldn't have been confused had it be printed this way.

In fact I wouldn't mind the file:line:column to be displayed every time.

Best,

Antoine



Le jeu. 3 sept. 2020 ? 00:19, Lionel Henry <lionel at rstudio.com> a ?crit
:
> Hello,
>
> The source references are useful for debugging tools because they
> allow linking to call sites in the source files.
>
> I agree the output can be confusing. Perhaps this could be fixed by
> tweaking the print method for calls. If the deparsed call doesn't
> match the srcref, both could be displayed along with file:line:column.
>
> ```
> #> f()
> #> <srcref:file.R:2:3>
> #> 1 + f()
> ```
>
> Best,
> Lionel
>
>
> On 9/2/20, Antoine Fabri <antoine.fabri at gmail.com> wrote:
> > Dear R-devel,
> >
> > I found this behavior disturbing, if `1 + f()` is called, `sys.call()`
> > called inside of `f` will return a quoted `f()` with a
"srcref" that
> prints
> > "1 + f()".
> >
> > I don't know which one is good but I don't think they can be
correct at
> the
> > same time.
> >
> > Here's a reproducible example:
> >
> > f <- function(){
> >   sc <- sys.call()
> >   print(sc)
> >   attr(sc, "srcref") <- NULL
> >   print(sc)
> >   1
> > }
> > f2 <- function() {
> >   1 + f()
> > }
> > f()
> > #> f()
> > #> f()
> > #> [1] 1
> > f2()
> > #> 1 + f()
> > #> f()
> > #> [1] 2
> >
> > Best,
> >
> > Antoine
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
>
	[[alternative HTML version deleted]]

>On Wednesday, September 2, 2020, 6:19:20 PM EDT, Lionel Henry <lionel at
rstudio.com> wrote:
>
>Hello,
>
>The source references are useful for debugging tools because they
>allow linking to call sites in the source files.
>
>I agree the output can be confusing. Perhaps this could be fixed by
>tweaking the print method for calls. If the deparsed call doesn't
>match the srcref, both could be displayed along with file:line:column.
>
>```
>#> f()
>#> <srcref:file.R:2:3>
>#> 1 + f()
>```
>
>Best,
>Lionel
Why print the mismatched srcref at all?? I find that confusing.
Just omit the srcref from display. Debugging tools can
still retrieve it and use the information, presumably.

Best,

Brodie.