Implement post render hooks; add hooks to tagList() #267

cpsievert · 2021-05-21T22:38:13Z

(I'm not 100% sure this is an avenue we want to pursue, but it does seem like a decent way to solve shiny::bootstrapLib()'s static rendering issues -- see rstudio/shiny#3402 for motivation)

This main point of this PR is to add a .postRenderHook -- the primary motivation for which is to provide a way to clean-up side-effects that may happen in .renderHook. It also adds the ability to attach hooks to tagList() (this will allow us to fully deprecate tagFunction() since we can now stop using it in shiny::bootstrapLib()). Here's an example:

foo <- tags$body(
  class = "foo",
  .renderHook = function(x) {
    if (isTRUE(getOption("bar"))) tagQuery(x)$addClass("bar")$allTags() else x
  }
)

bar <- tagList(
  .renderHook = function(x) {
    options("bar" = TRUE)
    x
  },
  .postRenderHook = function() {
    options("bar" = NULL)
  }
)

foo
#> <body class="foo"></body>
tagList(bar, foo)
#> <body class="foo bar"></body>

R/tags.R

cpsievert · 2021-05-25T22:42:55Z

@wch with 71ac6f9, .postRenderHook is now scheduling itself correctly now, but unfortunately I don’t see a way for .postRenderHook to modify its input with a single pass through the tree -- do you think that'll be an issue and/or see a way to do that?

R/tags.R

wch · 2021-05-27T00:43:04Z

We'll need some good unit tests to make sure the pre and post hooks are executed properly.

tests/testthat/test-tag-hooks.R

…uments

…d tags; get checks passing

…execution

cpsievert requested a review from wch May 21, 2021 22:49

cpsievert mentioned this pull request May 21, 2021

bootstrapLib() now always sets state on render and cleans up post static render rstudio/shiny#3402

Draft

wch mentioned this pull request May 25, 2021

renderHook should allow returning various types #268

Open

cpsievert commented May 25, 2021

View reviewed changes