.open and .close change delimiters

j_glue <- function(..., .envir = parent.frame()) {
  glue(..., .open = "<", .close = ">", .envir = .envir)
}

apples <- 1; bananas <- 2
json <- j_glue('
{
  "fruits": {
    "apples": <apples>,
    "bananas": <bananas>
  }
}')
jsonlite::fromJSON(json)

## $fruits
## $fruits$apples
## [1] 1
## 
## $fruits$bananas
## [1] 2

.transformer are robust

shell_transformer <- function(code, envir) {
  shQuote(eval(parse(text = code), envir))
}

glue_sh <- function(..., .envir = parent.frame()) {
  glue(..., .envir = .envir, .transformer = shell_transformer)
}

filename <- "test"
writeLines("hello!", filename)

cmd <- glue_sh("cat {filename}")
cmd

## cat 'test'

.transformer are useful

glue_fmt("π: {pi:.7}")

## π: 3.1415927

ratio <- sum(mtcars$gear == 3) / nrow(mtcars)

glue_fmt("{ratio * 100:.2}% of mtcars have 3 gears")

## 46.88% of mtcars have 3 gears

.transformer are fun 🎉

glue_ji("If life gives you :lemon: make :tropical_drink:")

## If life gives you 🍋 make 🍹

glue_ji("Many :hands*: make :light: :work:")

## Many 🤙👋👏👐🙌 make 🎃 🏢

Types of speed

• Speed of writing
• Speed of recall
• Speed of execution

glue is fast on single strings

bar <- "bar"
glue("foo{bar}")

glue is fast on lots of strings

bar <- rep("bar", 100000)
glue("foo{bar}")

glue is fast

• { } parsing in C
• performance dominated by parse() eval() and paste0().
• still slow? Vectorize!
• https://glue.tidyverse.org/articles/speed.html

glue_data() binds strings to any list / environment

library(magrittr)
head(mtcars) %>% 
  glue_data("{rownames(.)} has {cyl} cylinders and {hp}hp")

## Mazda RX4 has 6 cylinders and 110hp
## Mazda RX4 Wag has 6 cylinders and 110hp
## Datsun 710 has 4 cylinders and 93hp
## Hornet 4 Drive has 6 cylinders and 110hp
## Hornet Sportabout has 8 cylinders and 175hp
## Valiant has 6 cylinders and 105hp

glue_collapse() collapses vectors

glue_collapse(1:10, sep = " ")

## 1 2 3 4 5 6 7 8 9 10

glue_collapse(1:10, sep = " ", width = 10)

## 1 2 3 4...

glue_collapse(backtick(1:10), sep = ", ", last = " and ")

## `1`, `2`, `3`, `4`, `5`, `6`, `7`, `8`, `9` and `10`

glue_sql() quotes SQL strings

con <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
tbl <- DBI::Id(schema = "xyz", table = "iris")

glue_sql(
  "SELECT * FROM {`tbl`} WHERE species IN ({vals*})",
  vals = c("setosa", "versicolor"), .con = con)

## <SQL> SELECT * FROM `xyz`.`iris` WHERE species IN ('setosa', 'versicolor')

str_glue() is in

library(tidyverse)
str_glue("
  glue version: {packageVersion('glue')}
  tidyverse version: {packageVersion('tidyverse')}
  ")

## glue version: 1.2.0.9000
## tidyverse version: 1.2.1

• 60 reverse dependencies

• Monthly downloads

• dplyr, stringr, tidyr dependency, maybe already installed

install.packages("glue")

glue.tidyverse.org

adjective <-  c("luminous", "stylish", "super", "striking",
                "impressive", "fantastic")

glue("Have a {sample(adjective, 1)} day!")

## Have a super day!

@jimhester_   jimhester   jim.hester@rstudio.com