Dependency ordering

[cpsievert]

I'd like to use htmlwidgets::createWidget(dependencies = ...) to add a conditional dependency and I need that dependency to be placed above "official" dependencies declared in the YAML. Is there a slick way to do this that I'm unaware of?

[timelyportfolio]

Not that I know of considering lines. A not slick way is to wrap in a tagList and declare the dependencies there.

Interesting, since generally this flow from YAML to added dependencies is what I need.

[timelyportfolio]

Even less slick is to leave the YAML blank and declare all dependencies with createWidget(dependencies=...).

[timelyportfolio]

or get return value from htmltools::as.tags(plot_ly(...)) and then order the dependencies, so something like

p <- plot_ly(...)
p_tag <- htmltools::as.tags(p)

attr(p_tag,"html_dependencies") <- rev(attr(p_tag,"html_dependencies"))

[ramnathv]

Just so I understand @cpsievert, you can use the dependencies argument in createWidget, but the trouble is that it would place the dependency at the end of the other official dependencies. Is that correct?

[cpsievert]

yep

[ramnathv]

Okay. I don't see any other ways of doing it other than the ones proposed by @timelyportfolio. However, this use case does motivate the need to provide more control for placement of js/css assets. One idea I have toyed around with is introducing a priority argument in htmltools::htmlDependency. It would function like a z-index in html. I am not very clear how priorities would interact across widgets. @jjallaire @jcheng5 any thoughts on this?

[timelyportfolio]

Could we just provide a key/priority as @ramnathv suggests, and then sort by the key, so lines become? This would require a change to htmltools::htmlDependency also though.

dependencies <- c(widget_dependencies(class(x)[1], attr(x, 'package')),
  x$dependencies)

priority <- unique(
  unlist(
    lapply(
      dependencies,
      function(dep, i){
        if(is.null(dep$priority)){
          i
        } else as.numeric(dep$priority)
      },
      # more robust way of doing but for now just
      i = seq_len(length(dependencies))+100
    )
  )
)

html <- htmltools::attachDependencies(html, dependencies[order(priority,decreasing=FALSE)])

[timelyportfolio]

@cpsievert, I just thought of another option that I implemented in treebar lines. Create a custom *_html function and attach dependencies there. These will be added before the htmlwidget dependencies.

#' @keywords internal
treebar_html <- function(id, style, class, ...){
  htmltools::attachDependencies(
    htmltools::tagList(
      tags$div(id=id, style=style, class=class, ...)
    ),
    d3r::d3_dep_v4()
  )
}