<% a %> in knitr source code

[gaborcsardi]

lintr fails on knits with this:

Error in grep(pattern$chunk.begin, lines, perl = TRUE) :
  invalid 'pattern' argument

To reproduce:

cat("'<% a %>'\n", file = tmp <- tempfile());
lintr::lint(tmp)
#> Error in grep(pattern$chunk.begin, lines, perl = TRUE) :
#>   invalid 'pattern' argument

[jimhester]

This looks to be because in knitr the brew pattern has only an inline pattern, not a chunk start or end.

FWIW In devel lintr you can now pass strings directly to lintr::lint() if you end them with a newline.

 lintr::lint("'<% a %>'\n")
#> <text>:1:1: style: Only use double-quotes.
#> '<% a %>'
#> ^~~~~~~~~
#> <text>:2:1: style: Trailing blank lines are superfluous.
#> 
#> ^

[gaborcsardi]

Thanks!

Btw. knitr is nasty because its files are full of the knitr patterns, obviously. see #127

Do you need to use those patterns for parsing? I haven't looked much, but in reneral it would be great to parse without them, or at least not everything.

FWIW In devel lintr you can now pass strings directly to lintr::lint() if you end them with a newline.

But then how do I lint my files whose name ends with a newline? :P

[jimhester]

after 72f1985, 7fe7e90 knitr is now fully lintable and returns 5,569 lints with the default linters :).

Maybe not necessary for everything, it seemed easier to do it this way rather than have a file extension whitelist or something.

[gaborcsardi]

I don't mind the lints, just the errors....

Anyway, maybe I'll take a look, I'll pick up goodpractice soon again, and will do some lintr related stuff.