inline-markup {cli}R Documentation

About inline markup in the semantic cli

Description

To learn how to use cli’s semantic markup, start with the ‘Building a semantic CLI’ article at https://cli.r-lib.org.

Command substitution

All text emitted by cli supports glue interpolation. Expressions enclosed by braces will be evaluated as R code. See glue::glue() for details.

In addition to regular glue interpolation, cli can also add classes to parts of the text, and these classes can be used in themes. For example

cli_text("This is {.emph important}.")
#> This is important.                                                              

adds a class to the "important" word, class "emph". Note that in this case the string within the braces is usually not a valid R expression. If you want to mix classes with interpolation, add another pair of braces:

adjective <- "great"
cli_text("This is {.emph {adjective}}.")
#> This is great.                                                                  

An inline class will always create a span element internally. So in themes, you can use the span.emph CSS selector to change how inline text is emphasized:

cli_div(theme = list(span.emph = list(color = "red")))
adjective <- "nice and red"
cli_text("This is {.emph {adjective}}.")
#> This is nice and red.                                                           

Classes

The default theme defines the following inline classes:

ul <- cli_ul()
cli_li("{.emph Emphasized} text.")
cli_li("{.strong Strong} importance.")
cli_li("A piece of code: {.code sum(a) / length(a)}.")
cli_li("A package name: {.pkg cli}.")
cli_li("A function name: {.fn cli_text}.")
cli_li("A keyboard key: press {.kbd ENTER}.")
cli_li("A file name: {.file /usr/bin/env}.")
cli_li("An email address: {.email bugs.bunny@acme.com}.")
cli_li("A URL: {.url https://example.com}.")
cli_li("An environment variable: {.envvar R_LIBS}.")
cli_li("`mtcars` is {.obj_type_friendly {mtcars}}")
cli_end(ul)
#> • Emphasized text.                                                              
#> • Strong importance.                                                            
#> • A piece of code: `sum(a) / length(a)`.                                        
#> • A package name: cli.                                                          
#> • A function name: `cli_text()`.                                                
#> • A keyboard key: press [ENTER].                                                
#> • A file name: /usr/bin/env.                                                    
#> • An email address: bugs.bunny@acme.com.                                        
#> • A URL: <https://example.com>.                                                 
#> • An environment variable: `R_LIBS`.                                            
#> • `mtcars` is a data frame                                                      

You can add new classes by defining them in the theme, and then using them.

cli_div(theme = list(
  span.myclass = list(color = "lightgrey"),
  "span.myclass" = list(before = "<<"),
  "span.myclass" = list(after = ">>")))
cli_text("This is {.myclass in angle brackets}.")
cli_end()
#> This is <<in angle brackets>>.                                                  

Highlighting weird-looking values

Often it is useful to highlight a weird file or path name, e.g. one that starts or ends with space characters. The built-in theme does this for .file, .path and .email by default. You can highlight any string inline by adding the .q class to it.

The current highlighting algorithm

Collapsing inline vectors

When cli performs inline text formatting, it automatically collapses glue substitutions, after formatting. This is handy to create lists of files, packages, etc.

pkgs <- c("pkg1", "pkg2", "pkg3")
cli_text("Packages: {pkgs}.")
cli_text("Packages: {.pkg {pkgs}}.")
#> Packages: pkg1, pkg2, and pkg3.                                                 
#> Packages: pkg1, pkg2, and pkg3.                                                 

Class names are collapsed differently by default

x <- Sys.time()
cli_text("Hey, {.var x} has class {.cls {class(x)}}.")
#> Hey, `x` has class <POSIXct/POSIXt>.                                            

By default cli truncates long vectors. The truncation limit is by default twenty elements, but you can change it with the vec-trunc style.

nms <- cli_vec(names(mtcars), list("vec-trunc" = 5))
cli_text("Column names: {nms}.")
#> Column names: mpg, cyl, disp, …, gear, and carb.                                

Formatting values

The val inline class formats values. By default (c.f. the built-in theme), it calls the cli_format() generic function, with the current style as the argument. See cli_format() for examples.

str is for formatting strings, it uses base::encodeString() with double quotes.

Escaping ⁠{⁠ and ⁠}⁠

It might happen that you want to pass a string to ⁠cli_*⁠ functions, and you do not want command substitution in that string, because it might contain ⁠{⁠ and ⁠}⁠ characters. The simplest solution for this is to refer to the string from a template:

msg <- "Error in if (ncol(dat$y)) {: argument is of length zero"
cli_alert_warning("{msg}")
#> ! Error in if (ncol(dat$y)) {: argument is of length zero                       

If you want to explicitly escape ⁠{⁠ and ⁠}⁠ characters, just double them:

cli_alert_warning("A warning with {{ braces }}.")
#> ! A warning with { braces }.                                                    

See also examples below.

Pluralization

All cli commands that emit text support pluralization. Some examples:

ndirs <- 1
nfiles <- 13
pkgs <- c("pkg1", "pkg2", "pkg3")
cli_alert_info("Found {ndirs} director{?y/ies} and {nfiles} file{?s}.")
cli_text("Will install {length(pkgs)} package{?s}: {.pkg {pkgs}}")
#>  Found 1 directory and 13 files.                                               
#> Will install 3 packages: pkg1, pkg2, and pkg3                                   

See pluralization for details.

Wrapping

Most cli containers wrap the text to width the container's width, while observing margins requested by the theme.

To avoid a line break, you can use the UTF_8 non-breaking space character: ⁠\u00a0⁠. cli will not break a line here.

To force a line break, insert a form feed character: ⁠\f⁠ or ⁠\u000c⁠. cli will insert a line break there.


[Package cli version 3.6.2 Index]