Using variable number of input fields in shiny page

Question

My problem is as follows:

I have a shiny application that displays a variable number of output elements based on user input (as, for example, is detailed in: dynamic

Answer 1

While I don't find it to be an ideal solution, assigning:

output[[modifier]] <- renderUI({selectInput(
                                      inputId = modifier,
                                      label="select how to display",
                                      choices = c("plot","table"),
                                      selected = input[[modifier]])})

solves the problem, though I'd be happy to get a better solution (specifically one that avoids the construction of the input object every time anew).