Implement alternative delimiters

Fixes #23

NEWS.md

@@ -1,5 +1,9 @@
 # glue 1.0.0.9000
 
+`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).
 
 # glue 0.0.0.9000

R/glue.R

@@ -36,6 +36,10 @@
 #' # `glue_data()` is useful in magrittr pipes
 #' library(magrittr)
 #' mtcars %>% glue_data("{rownames(.)} has {hp} hp")
+#'
+#' # Alternative delimiters can also be used if needed
+#' one <- "1"
+#' glue("The value of $e^{2\\pi i}$ is $<<one>>$.", .open = "<<", .close = ">>")
 #' @useDynLib glue glue_
 #' @name glue
 #' @export
@@ -86,8 +90,8 @@ to_data <- glue_data
 
 #' @export
 #' @rdname glue
-glue <- function(..., .sep = "", .envir = parent.frame()) {
-  glue_data(.x = NULL, ..., .sep = .sep, .envir = .envir)
+glue <- function(..., .sep = "", .envir = parent.frame(), .open = "{", .close = "}") {
+  glue_data(.x = NULL, ..., .sep = .sep, .envir = .envir, .open = .open, .close = .close)
 }
 
 #' @rdname glue

README.Rmd

@@ -93,6 +93,12 @@ name <- "Fred"
 glue("My name is {name}, not {{name}}.")
 ```
 
+##### Alternative delimiters can be specified with `.open` and `.close`.
+```{r}
+one <- "1"
+glue("The value of $e^{2\\pi i}$ is $<<one>>$.", .open = "<<", .close = ">>")
+```
+
 ##### All valid R code works in expressions, including braces and escaping.
 Backslashes do need to be doubled just like in all R strings.
 ```{r}

README.md

@@ -79,7 +79,7 @@ glue("
 
   ")
 #> 
-#>   leading or trailing newlines can be added explicitly
+#> leading or trailing newlines can be added explicitly
 ```
 
 ##### `\\` at the end of a line continues it without a new line.
@@ -101,6 +101,14 @@ glue("My name is {name}, not {{name}}.")
 #> My name is Fred, not {name}.
 ```
 
+##### Alternative delimiters can be specified with `.open` and `.close`.
+
+``` r
+one <- "1"
+glue("The value of $e^{2\\pi i}$ is $<<one>>$.", .open = "<<", .close = ">>")
+#> The value of $e^{2\pi i}$ is $1$.
+```
+
 ##### All valid R code works in expressions, including braces and escaping.
 
 Backslashes do need to be doubled just like in all R strings.