Changelog

Breaking changes

New glue_sql_collapse() function to collapse inputs and return a DBI::SQL() object (#103).
glue() gains a new .comment argument, to control the comment character (#193).
glue() gains a new .null argument, to control the value to replace NULL values with (#217, @echasnovski).

sql_quote_transformer() is now allows whitespace after the trailing * (#218).
compare_proxy.glue() method defined so glue objects can be compared to strings in testthat 3e without errors (#212)
print.glue() no longer prints an empty newline for 0 length inputs (#214)
Unterminated comments in glue expression now throw an error (#227, @gaborcsardi)
Unterminated quotes in glue expressions now throw an error (#226, @gaborcsardi)

glue_safe() gives a slightly nicer error message
The required version of R is now 3.2 (#189)
glue_sql() now collapses DBI::SQL() elements correctly (#192 @shrektan)
The internal compare() method gains a ... argument, for compatibility with testthat 3.0.0

Internal changes for compatibility with vctrs 0.3.0 (#187).
glue_sql() now replaces missing values correctly when collapsing values (#185).
glue_sql() now always preserves the type of the column even in the presence of missing values (#130)

.envir = NULL is now supported and is equivalent to passing .envir = emptyenv() (#140)
New glue_safe() and glue_data_safe() functions, safer versions of glue() that do not execute code, only look up values (using get()). These alternatives are useful for things like shiny applications where you do not have control of the input for your glue expressions. (#140)
Fixed memory access issue and memory leaks found by valgrind.

glue now implements vctrs methods. This ensures that vectors of glue strings are compatible with tidyverse packages like tidyr (r-lib/tidyselect#170, tidyverse/tidyr#773, @lionel-).
Fix a LTO type mismatch warning (#146)
glue_sql() now quotes lists of values appropriate to their type, rather than coercing all values to characters (#153)
glue_data() now implicitly coerces .x to a list.
glue() gains the .trim argument, like glue_data().
single_quote() double_quote() and backtick() all return NA for NA inputs (#135).
Improve trim()’s handling of lines containing only indentation (#162, #163, @alandipert)

glue() now has a + method to combine strings.
glue_sql() now collapses zero-length vector into DBI::SQL("NULL") (#134 @shrektan).

The evaluate() function has been removed. Changes elsewhere in glue made the implementation trivial so it was removed for clarities sake. Previous uses can be replaced by eval(parse(text = text), envir).
collapse() has been renamed to glue_collapse() to avoid namespace collisions with dplyr::collapse().

compare.glue() was added, to make it easier to use glue objects in testthat::expect_equal() statements.
glue_col() and glue_data_col() functions added to display strings with color.

Glue now throws an informative error message when it cannot interpolate a function into a string (#114, @haleyjeppson & @ijlyttle).
Glue now evaluates unnamed arguments lazily with delayedAssign(), so there is no performance cost if an argument is not used. (#83, @egnha).
Fixed a bug where names in the assigned expression of an interpolation variable would conflict with the name of the variable itself (#89, @egnha).
Do not drop the glue class when subsetting (#66).
Fix glue() and collapse() always return UTF-8 encoded strings (#81, @dpprdan)

The implementation has been tweaked to be slightly faster in most cases.
glue() now has a .transformer argument, which allows you to use custom logic on how to evaluate the code within glue blocks. See vignette("transformers") for more details and example transformer functions.
glue() now returns NA if any of the results are NA and .na is NULL. Otherwise NA values are replaced by the value of .na.
trim() to use the trimming logic from glue is now exported.
glue_sql() and glue_data_sql() functions added to make constructing SQL statements with glue safer and easier.
glue() is now easier to use when used within helper functions such as lapply.
Fix when last expression in glue() is NULL.

Fix for PROTECT errors when resizing output strings.
glue() always returns ‘UTF-8’ strings, converting inputs if in other encodings if needed.
to() and to_data() have been removed.
glue() and glue_data() can now take alternative delimiters to { and }. This is useful if you are writing to a format that uses a lot of braces, such as LaTeX. (#23)
collapse() now returns 0 length output if given 0 length input (#28).