On 14/06/2017 5:58 AM, Andreas Kersting wrote:
Hi,
I would really like to have a way to split long string literals across
multiple lines in R.
I don't understand why you require the string to be a literal. Why not
construct the long string in an expression like
paste0("aaa",
"bbb")
? Surely the execution time of the paste0 call is negligible.
Duncan Murdoch
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 "
"bbb")
or
("aaa ",
"bbb")
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?
Regards,
Andreas
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