glue() and glue_data() documentation inaccurate on what trimming happens

[ha0ye]

The help file for glue() and glue_data() has:

Leading whitespace and blank lines from the first and last lines are automatically trimmed.

but calls the trim() function by default (when .trim == TRUE), which states:

Leading and trailing whitespace from the first and last lines is removed.

Recommended fix

Update the documentation -- adjust the text to indicate that both leading and trailing whitespace and blank lines are automatically trimmed

[ha0ye]

Update

Sorry, checked some other things. Seems that the only trimming is on leading and trailing blank lines, and not on "whitespace" as typically defined. See below reprex.

library(glue)

glue(" {letters[1:3]}")
#>  a
#>  b
#>  c
glue("{letters[1:3]} ")
#> a 
#> b 
#> c
identical(as.character(glue("{letters[1:3]} ")), c("a ", "b ", "c "))
#> [1] TRUE
glue("\n{letters[1:3]}")
#> a
#> b
#> c
glue("{letters[1:3]}\n")
#> a
#> b
#> c

^{Created on 2022-04-16 by the reprex package (v2.0.1)}

[ha0ye]

Update 2

Some more confusing examples:

library(glue)
glue("\n  {letters[1:3]}")
#> a
#> b
#> c
glue("  {letters[1:3]}")
#>   a
#>   b
#>   c

^{Created on 2022-04-16 by the reprex package (v2.0.1)}

[hadley]

Looks like this has already been clarified in https://glue.tidyverse.org/reference/trim.html

[mtmorgan]

I'm also having trouble understanding what trim() does. The glue help page seems to point to PEP-257 and the Python implementation in the section at https://peps.python.org/pep-0257/#handling-docstring-indentation. But Python and glue::trim() behave differently with respect to leading / trailing whitespace, with Python doing more or less what I expect. Here are some example with Python >>> and R >

## leading / trailing whitespace
>>> trim("foo\n\n")
'foo'
> trim("foo\n\n")
[1] "foo\n"

>>> trim(" foo ")
'foo'
> trim(" foo ")
[1] " foo "

## indentation -- consistent spacing but not trailing whitespace
>>> trim("\n  foo\n    bar\n\n")
'foo\n  bar'
> trim("\n  foo\n    bar\n\n")
[1] "foo\n  bar\n"