introduce decorators for tm_a_pca

[m7pr]

Part of #863

Working Example

devtools::load_all("../teal")
devtools::load_all(".")
plot_title <- teal_transform_module(
  server = make_teal_transform_server(expression({
    plot <- plot + ggtitle("Custom title")
  }))
)

# general data example
data <- teal_data()
data <- within(data, {
  require(nestcolor)
  USArrests <- USArrests
})

app <- init(
  data = data,
  modules = modules(
    tm_a_pca(
      "PCA",
      dat = data_extract_spec(
        dataname = "USArrests",
        select = select_spec(
          choices = variable_choices(
            data = data[["USArrests"]], c("Murder", "Assault", "UrbanPop", "Rape")
          ),
          selected = c("Murder", "Assault"),
          multiple = TRUE
        ),
        filter = NULL
      ),
      decorators = list(plot_title)
    )
  )
)
if (interactive()) {
  shinyApp(app$ui, app$server)
}

[averissimo]

Problem solved, 1 suggestion