[Rd] [WISH / PATCH] possibility to split string literals across multiple lines

Andreas Kersting r-devel at akersting.de
Wed Jun 14 12:58:38 CEST 2017


I would really like to have a way to split long string literals across 
multiple lines in R.

Currently, if a string literal spans multiple lines, there is no way to 
inhibit the introduction of newline characters:

 > "aaa
+ bbb"
[1] "aaa\nbbb"

If a line ends with a backslash, it is just ignored:

 > "aaa\
+ bbb"
[1] "aaa\nbbb"

We could use this fact to implement string splitting in a fairly 
backward-compatible way, since currently such trailing backslashes 
should hardly be used as they do not have any effect. The attached patch 
makes the parser ignore a newline character directly following a backslash:

 > "aaa\
+ bbb"
[1] "aaabbb"

I personally would also prefer if leading blanks (spaces and tabs) in 
the second line are ignored to allow for proper indentation:

 >   "aaa \
+    bbb"
[1] "aaa bbb"

 >   "aaa\
+    \ bbb"
[1] "aaa bbb"

This is also implemented by this patch.

An alternative approach could be to have something like

("aaa "


("aaa ",

be interpreted as "aaa bbb".

I don't know the ins and outs of the parser of R (hence: please very 
carefully review the attached patch), but I guess this would be more 
work to implement!?

What do you think? Is there anybody else who is missing this feature in 
the first place?

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