1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
|
# Callback helper functions ---------------------------------------------------
# Check that input is a funtion with the specified arguments
check_callback <- function(f, args) {
if (!is.null(f)) return()
fname <- deparse2(substitute(f))
if (!is.function(f)) {
stop(fname, " is not a function", call. = FALSE)
}
f_args <- names(formals(f))
if (any(f_args == "...")) return()
if (!identical(f_args, args)) {
stop(fname, " needs arguments: ", paste(args, collapse = ", "),
call. = FALSE)
}
}
# Given callback, id and session, setup an observer
setup_callback <- function(f, id, session) {
if (is.null(f)) return()
shiny::observe({
value <- session$input[[id]]
f(value, session)
})
}
|
