links: cli hyperlinks

In cli: Helpers for Developing Command Line Interfaces

cli hyperlinks

Description

Certain cli styles create clickable links, if your IDE or terminal supports them.

Note: hyperlinks are currently experimental

The details of the styles that create hyperlinks will prrobably change in the near future, based on user feedback.

About the links in this manual page

The hyperlinks that are included in this manual are demonstrative only, except for the ⁠https:⁠ links. They look like a hyperlink, and you can click on them, but they do nothing. I.e. a .run link will not run the linked expression if you click on it.

Hyperlink Support

As of today, the latest release of RStudio (version v2022.07.0+548) supports all hyperlink types discussed here. Certain terminals, e.g. iTerm on macOS, Linux terminals based on VTE (GNOME terminal) support .href, .email and .file links.

You can use ansi_has_hyperlink_support() to check if your terminal or IDE has hyperlink support in general, and ansi_hyperlink_types() to check if various types of hyperlinks are supported.

If your hyperlink support is not detected properly in your IDE or terminal, please open a cli issue at https://github.com/r-lib/cli/issues.

Link text

Before we delve into the various types of hyperlinks, a general comment about link texts. Some link styles support a custom link text:

• .href

• .help

• .topic

• .vignette

• .run

Others, i.e. .email, .file, .fun and .url do not support custom link text.

The generic syntax for link text is the same as for Markdown hyperlinks:

{.style [link text](url)}

Vectorization

Note that it is not possible to add link text to a vector of URLs. E.g. this will create a list of three URLs, all clickable:

urls <- paste0("https://httpbin.org/status/", c(200, 403, 404))
cli::cli_text("Some httpbin URLs: {.url {urls}}.")

#> Some httpbin URLs: <https://httpbin.org/status/200>,                            
#> <https://httpbin.org/status/403>, and                                           
#> <https://httpbin.org/status/404>.                                               

But it is not possible to use a different link text for them.

What if hyperlinks are not available?

If ANSI hyperlinks are not available, then the link text for of these styles outputs both the link text and the URL in a (hopefully) helpful way. See examples below.

URLs

There are two cli styles to link to generic URLs. .url does not allow custom link text, but ⁠\href⁠ does.

cli_text(
  "See the cli homepage at {.url https://cli.r-lib.org} for details."
)

#> See the cli homepage at <https://cli.r-lib.org> for details.                    

cli_text(
  "See the {.href [cli homepage](https://cli.r-lib.org)} for details."
)

#> See the cli homepage for details.                                               

Without hyperlink support

This is how these links look without hyperlink support:

local({
  withr::local_options(cli.hyperlink = FALSE)
  cli_text(
    "See the cli homepage at {.url https://cli.r-lib.org} for details."
  )
  cli_text(
    "See the {.href [cli homepage](https://cli.r-lib.org)} for details."
  )
})

#> See the cli homepage at <https://cli.r-lib.org> for details.                    
#> See the cli homepage (<https://cli.r-lib.org>) for details.                     

URL encoding

Note that cli does not encode the url, so you might need to call utils::URLencode() on it, especially, if it is substituted in via {}.

weirdurl <- utils::URLencode("https://example.com/has some spaces")
cli_text("See more at {.url {weirdurl}}.")

#> See more at <https://example.com/has%20some%20spaces>.                          

Files

The .file style now automatically creates a ⁠file:⁠ hyperlink. Because ⁠file:⁠ hyperlinks must contain an absolute path, cli tries to convert relative paths, and paths starting with ~ to aboslute path.

cli_text("... edit your {.file ~/.Rprofile} file.}")

#> ... edit your ~/.Rprofile file.}                                                

Link text

.file cannot use a custom link text. If you custom link text, then you can use .href with a ⁠file:⁠ URL.

prof <- path.expand("~/.Rprofile")
cli_text("... edit your {.href [R profile](file://{prof})}.")

#> ... edit your R profile.                                                        

Line and column numbers

You may add a line number to a file name, separated by :. Handlers typically place the cursor at that line after opening the file. You may also add a column number, after the line number, separated by another :.

cli_text("... see line 5 in {.file ~/.Rprofile:5}.")

#> ... see line 5 in ~/.Rprofile:5.                                                

Default handler

In RStudio ⁠file:⁠ URLs open within RStudio. If you click on a file link outside of RStudio, typically the operating system is consulted for the application to open it.

Without hyperlink support

One issue with using .href file files is that it does not look great if hyperlinks are not available. This will be improved in the future:

local({
  withr::local_options(cli.hyperlink = FALSE)
  prof <- path.expand("~/.Rprofile")
  cli_text("... edit your {.href [R profile](file://{prof})}.")
})

#> ... edit your R profile (<file:///Users/gaborcsardi/.Rprofile>).                

Links to the manual

.fun automatically creates links to the manual page of the function, provided the function name is in the packagename::functionname form:

cli::cli_text("... see {.fun stats::lm} to learn more.")

#> ... see `stats::lm()` to learn more.                                            

Link text

For a custom link text, use .help instead of .fun.

cli::cli_text("... see {.help [{.fun lm}](stats::lm)} to learn more.")

#> ... see `lm()` to learn more.                                                   

Without hyperlink support

The same message without hyperlink support looks like this:

local({
  withr::local_options(cli.hyperlink = FALSE)
  cli::cli_text("... see {.help [{.fun lm}](stats::lm)} to learn more.")
})

#> ... see `lm()` (`?stats::lm()`) to learn more.                                  

Topics

To link to a help topic that is not a function, use .topic:

cli::cli_text("... the tibble options at {.help tibble::tibble_options}.")

#> ... the tibble options at tibble::tibble_options.                               

.topic support link text.

Vignettes

To link to a vignette, use .vignette:

cli::cli_text("... see the {.vignette tibble::types} vignette.")

#> ... see the tibble::types vignette.                                             

Click to run code

RStudio also supports a special link type that runs R code in the current R session upon clicking.

You can create these links with .run:

cli::cli_text("Run {.run testthat::snapshot_review()} to review")

#> Run testthat::snapshot_review() to review                                       

Link text

Sometimes you want to show a slightly different expression in the link, than the one that is evaluated. E.g. the evaluated expression probably needs to qualify packages with ::, but you might not want to show this:

cli::cli_text(
  "Run {.run [snapshot_review()](testthat::snapshot_review())} to review"
)

#> Run snapshot_review() to review                                                 

Security considerations

To make .run hyperlinks more secure, RStudio with not run code

• that is not in the pkg::fun(args) form,

• if args contains (, ⁠)⁠ or ⁠;⁠,

• if it calls a core package (base, stats, etc.),

• if it calls a package that is not loaded, and it is not one of testthat, devtools, usethis, or rlang, which are explicitly allowed.

cli documentation built on March 31, 2023, 9:04 p.m.