R devel - Jun 2025 - Specifying a long string literal across several lines

On 5/28/25 04:15, Pavel Krivitsky via R-devel wrote:
> Dear All,
>
> Perhaps this should go in r-package-devel, but I suspect that this is
> going to turn into a feature request, and I want to run it by the list
> before filing it in the Bugzilla.
>
> I would like to specify a long string literal without making the line
> of code too long. In R,
>
> "abc
> def"
>
> yields the string "abc\def", and, as far as I can tell, there is
no
> mechanism for preventing it from inserting a newline into the string.
>
> Putting a backslash before the newline, i.e.,
>
> "abc\
> def"
>
> eliminates the newline in (that I know of) C/C++, Python, and Julia,
> but it makes no difference in R.
>
> The implicit concatenation of Python and C/C++, e.g., "abc"
"def", is a
> syntax error as well in R.
>
> It is, of course, possible to use paste0(), but is there a more concise
> built-in mechanism in R of which I am not aware?
>
> If not, I think it would make sense to bring R in line with the others.
> Currently, backslash and no backslash before a newline behave
> identically (at least as far as I can tell), so I doubt that a
> nontrivial amount of code relies on the current behaviour. [1]
What would be real example of a long string literal you would want to 
enter this way?

For entering a long text with newlines, one can use raw strings in R 
(see ?Quotes) - but there you would see the newlines and indentation. 
I've seen code where? "paste0" has been aliased to a local
function
named with a single letter to make concatenation more concise.

Best
Tomas
>
> 				Any thoughts?
> 				Pavel
>
> [1] On the off chance that it does, it should easy to check by
> searching for "\\\n" in package sources, because a backslash
before a
> newline is a syntax error outside a string.
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

Tomas,

Here is a good example of where this functionality would be useful:
https://github.com/R-ArcGIS/arcgislayers/blob/2b29f4c254e7e5a1dadce8d4b0015a70dfae39d4/R/arc-open.R#L19-L56

In order to prevent R CMD check notes I have to use `paste0()` to
concatenate long URLs. If we were able to use `\` to
separate the string across multiple lines, it would make the solution much
nicer!

On Mon, Jun 2, 2025 at 3:19?AM Tomas Kalibera <tomas.kalibera at
gmail.com>
wrote:
>
> On 5/28/25 04:15, Pavel Krivitsky via R-devel wrote:
> > Dear All,
> >
> > Perhaps this should go in r-package-devel, but I suspect that this is
> > going to turn into a feature request, and I want to run it by the list
> > before filing it in the Bugzilla.
> >
> > I would like to specify a long string literal without making the line
> > of code too long. In R,
> >
> > "abc
> > def"
> >
> > yields the string "abc\def", and, as far as I can tell,
there is no
> > mechanism for preventing it from inserting a newline into the string.
> >
> > Putting a backslash before the newline, i.e.,
> >
> > "abc\
> > def"
> >
> > eliminates the newline in (that I know of) C/C++, Python, and Julia,
> > but it makes no difference in R.
> >
> > The implicit concatenation of Python and C/C++, e.g., "abc"
"def", is a
> > syntax error as well in R.
> >
> > It is, of course, possible to use paste0(), but is there a more
concise
> > built-in mechanism in R of which I am not aware?
> >
> > If not, I think it would make sense to bring R in line with the
others.
> > Currently, backslash and no backslash before a newline behave
> > identically (at least as far as I can tell), so I doubt that a
> > nontrivial amount of code relies on the current behaviour. [1]
>
> What would be real example of a long string literal you would want to
> enter this way?
>
> For entering a long text with newlines, one can use raw strings in R
> (see ?Quotes) - but there you would see the newlines and indentation.
> I've seen code where  "paste0" has been aliased to a local
function
> named with a single letter to make concatenation more concise.
>
> Best
> Tomas
>
> >
> >                               Any thoughts?
> >                               Pavel
> >
> > [1] On the off chance that it does, it should easy to check by
> > searching for "\\\n" in package sources, because a backslash
before a
> > newline is a syntax error outside a string.
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]