Shiny API v2 - modern aliases for Shiny UI/output functions

[gadenbuie]

Could bslib provide modern aliases for Shiny UI functions? This PR aims to answer that question by starting with aliases for Shiny functions that have also been ported to Shiny for Python, using naming conventions that are familiar to tidyverse users and consistent with the Shiny for Python API (these are generall well-aligned).

In addition to helping to nudge naming conventions away from camel case, this PR will also help give bslib some flexibility in providing its own implementations of these inputs. This will make it easier for bslib to eventually provide inputs tailored to specific Bootstrap versions or to provide alternate implementations that fix Shiny issues that are relevant to bslib but harder to address in Shiny directly.

To that last point, there are some deviations from core Shiny in this PR:

• id is used instead of inputId or outputId.
• session is not the first argument of the update_*() functions, instead it's the last.
• ... are added in many places, generally following Shiny for Python's * placement. This matches practical usage and makes it easier for us to adjust function signatures in the future.
• We skip Shiny's icon validation in input_action_button() and input_action_link(), making it possible to use bsicon::bs_icon() and others.

Remaining work:

• modals
• notifications
• progress bars

App demo/test

library(shiny)
pkgload::load_all()
library(bslib)

ui <- page_navbar(
  theme = bs_theme() |>
    bs_add_rules("
    h2 {
      border-top: 1px solid var(--bs-border-color-translucent);
      padding-top: 0.5rem;
      font-family: var(--bs-font-monospace);
    }
    h2:not(:first-child) {
      margin-top: 3rem;
    }"),

  title = "Shiny Aliases",
  # selected = "Outputs",
  fillable = TRUE,
  padding = 0,

  nav_panel(
    "Inputs",
    div(
      as_fill_item(),
      class = "overflow-auto p-3",
      h2("input_action_button"),
      layout_columns(
        input_action_button(
          "action_button",
          "Action Button",
          icon = bsicons::bs_icon("cash")
        ),
        output_text_verbatim("debug_action_button")
      ),
      h2("input_action_link"),
      layout_columns(
        input_action_link(
          "action_link",
          "Action Link",
          icon = bsicons::bs_icon("truck")
        ),
        output_text_verbatim("debug_action_link")
      ),
      h2("input_checkbox"),
      layout_columns(
        input_checkbox("checkbox", "Checkbox"),
        output_text_verbatim("debug_checkbox")
      ),
      h2("input_checkbox_group"),
      layout_columns(
        input_checkbox_group(
          "checkbox_group",
          "Checkbox Group",
          choices = c("Option 1", "Option 2")
        ),
        output_text_verbatim("debug_checkbox_group")
      ),
      h2("input_date"),
      layout_columns(
        input_date("date", "Date Input"),
        output_text_verbatim("debug_date")
      ),
      h2("input_date_range"),
      layout_columns(
        input_date_range("date_range", "Date Range Input"),
        output_text_verbatim("debug_date_range")
      ),
      h2("input_numeric"),
      layout_columns(
        input_numeric("numeric", "Numeric Input", 42),
        output_text_verbatim("debug_numeric")
      ),
      h2("input_password"),
      layout_columns(
        input_password("password", "Password Input"),
        output_text_verbatim("debug_password")
      ),
      h2("input_radio_buttons"),
      layout_columns(
        input_radio_buttons(
          "radio_buttons",
          "Radio Buttons",
          choices = c("Option 1", "Option 2")
        ),
        output_text_verbatim("debug_radio_buttons")
      ),
      h2("input_select"),
      layout_columns(
        input_select(
          "select",
          "Select Input",
          choices = c("Option 1", "Option 2")
        ),
        output_text_verbatim("debug_select")
      ),
      h2("input_selectize"),
      layout_columns(
        input_selectize(
          "selectize",
          "Selectize Input",
          choices = c("Option 1", "Option 2")
        ),
        output_text_verbatim("debug_selectize")
      ),
      h2("input_slider"),
      layout_columns(
        div(
          input_slider(
            "slider",
            "Slider Input",
            min = 0,
            max = 100,
            value = 50
          ),
          input_slider(
            "range_slider",
            "Range Slider Input",
            min = 0,
            max = 100,
            value = c(25, 75)
          )
        ),
        output_text_verbatim("debug_slider")
      ),
      h2("input_text"),
      layout_columns(
        input_text("text", "Text Input"),
        output_text_verbatim("debug_text")
      ),
      h2("input_text_area"),
      layout_columns(
        input_text_area("text_area", "Text Area Input"),
        output_text_verbatim("debug_text_area")
      )
    )
  ),

  nav_panel(
    "Outputs",
    div(
      as_fill_item(),
      class = "overflow-auto p-3",
      layout_column_wrap(
        width = 400,
        heights_equal = "row",
        div(
          h2("output_image"),
          output_image("output_image")
        ),
        div(
          h2("output_plot"),
          output_plot("output_plot")
        ),
        div(
          h2("output_table"),
          output_table("output_table")
        ),
        div(
          h2("output_text"),
          output_text("output_text")
        ),
        div(
          h2("output_text_verbatim"),
          output_text_verbatim("output_text_verbatim")
        ),
        div(
          h2("output_ui"),
          output_ui("output_ui")
        )
      )
    )
  )
)


server <- function(input, output, session) {
  output$debug_action_button <- render_text_verbatim({
    input$action_button
  })
  output$debug_action_link <- render_text_verbatim({
    input$action_link
  })
  output$debug_checkbox <- render_text_verbatim({
    input$checkbox
  })
  output$debug_checkbox_group <- render_text_verbatim({
    input$checkbox_group
  })
  output$debug_date <- render_text_verbatim({
    input$date
  })
  output$debug_date_range <- render_text_verbatim({
    input$date_range
  })
  output$debug_numeric <- render_text_verbatim({
    input$numeric
  })
  output$debug_password <- render_text_verbatim({
    input$password
  })
  output$debug_radio_buttons <- render_text_verbatim({
    input$radio_buttons
  })
  output$debug_select <- render_text_verbatim({
    input$select
  })
  output$debug_selectize <- render_text_verbatim({
    input$selectize
  })
  output$debug_slider <- render_text_verbatim({
    list(
      slider = input$slider,
      range_slider = input$range_slider
    )
  })
  output$debug_text <- render_text_verbatim({
    input$text
  })
  output$debug_text_area <- render_text_verbatim({
    input$text_area
  })

  # Outputs ---------------------------------------------------------------
  output$output_text <- render_text({
    input$action_button
    paste(lorem::ipsum(1, 1))
  })

  output$output_image <- renderImage(
    {
      # A temp file to save the output. It will be deleted after renderImage
      # sends it, because deleteFile=TRUE.
      outfile <- tempfile(fileext = ".png")

      # Generate a png
      png(outfile, width = 400, height = 400)
      hist(rnorm(input$slider))
      dev.off()

      # Return a list
      list(
        src = outfile,
        alt = "This is alternate text"
      )
    },
    deleteFile = TRUE
  )

  output$output_plot <- render_plot({
    plot(
      runif(50, input$range_slider[1], input$range_slider[2]),
      rnorm(50)
    )
  })

  output$output_table <- render_table({
    input$action_link
    data.frame(
      id = 1:5,
      x = runif(5),
      y = rnorm(5)
    )
  })

  output$output_text_verbatim <- render_text_verbatim({
    summary(if (input$checkbox) mtcars else cars)
  })

  output$output_ui <- render_ui({
    tags$ul(
      tags$li(tags$code("select"), "-", input$select),
      tags$li(tags$code("selectize"), "-", input$selectize),
    )
  })
}

shinyApp(ui, server)