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

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]

				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.

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.
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