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Documentation to come in a later PR Co-authored-by: Barret Schloerke <schloerke@gmail.com> Co-authored-by: Winston Chang <winston@stdout.org>
92 lines
3.6 KiB
R
92 lines
3.6 KiB
R
% Generated by roxygen2: do not edit by hand
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% Please edit documentation in R/shinywrappers.R
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\name{createRenderFunction}
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\alias{createRenderFunction}
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\title{Implement render functions}
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\usage{
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createRenderFunction(
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func,
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transform = function(value, session, name, ...) value,
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outputFunc = NULL,
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outputArgs = NULL,
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cacheHint = "auto",
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cacheWriteHook = NULL,
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cacheReadHook = NULL
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)
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}
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\arguments{
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\item{func}{A function without parameters, that returns user data. If the
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returned value is a promise, then the render function will proceed in async
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mode.}
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\item{transform}{A function that takes four arguments: \code{value},
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\code{session}, \code{name}, and \code{...} (for future-proofing). This
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function will be invoked each time a value is returned from \code{func},
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and is responsible for changing the value into a JSON-ready value to be
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JSON-encoded and sent to the browser.}
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\item{outputFunc}{The UI function that is used (or most commonly used) with
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this render function. This can be used in R Markdown documents to create
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complete output widgets out of just the render function.}
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\item{outputArgs}{A list of arguments to pass to the \code{uiFunc}. Render
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functions should include \code{outputArgs = list()} in their own parameter list,
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and pass through the value to \code{markRenderFunction}, to allow app authors to
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customize outputs. (Currently, this is only supported for dynamically
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generated UIs, such as those created by Shiny code snippets embedded in R
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Markdown documents).}
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\item{cacheHint}{One of \code{"auto"}, \code{FALSE}, or some other information to
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identify this instance for caching using \code{\link[=bindCache]{bindCache()}}. If \code{"auto"}, it
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will try to automatically infer caching information. If \code{FALSE}, do not
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allow caching for the object. Some render functions (such as \link{renderPlot})
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contain internal state that makes them unsuitable for caching.}
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\item{cacheWriteHook}{Used if the render function is passed to \code{bindCache()}.
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This is an optional callback function to invoke before saving the value
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from the render function to the cache. This function must accept one
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argument, the value returned from \code{renderFunc}, and should return the value
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to store in the cache.}
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\item{cacheReadHook}{Used if the render function is passed to \code{bindCache()}.
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This is an optional callback function to invoke after reading a value from
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the cache (if there is a cache hit). The function will be passed one
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argument, the value retrieved from the cache. This can be useful when some
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side effect needs to occur for a render function to behave correctly. For
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example, some render functions call \code{\link[=createWebDependency]{createWebDependency()}} so that Shiny
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is able to serve JS and CSS resources.}
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}
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\value{
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An annotated render function, ready to be assigned to an
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\code{output} slot.
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}
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\description{
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This function is a wrapper for \code{\link[=markRenderFunction]{markRenderFunction()}} which provides support
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for async computation via promises. It is recommended to use
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\code{createRenderFunction()} instead of \code{markRenderFunction()}.
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}
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\examples{
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# A very simple render function
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renderTriple <- function(expr) {
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func <- quoToFunction(rlang::enquo0(expr))
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createRenderFunction(
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func,
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transform = function(value, session, name, ...) {
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paste(rep(value, 3), collapse=", ")
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},
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outputFunc = textOutput
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)
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}
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# Test render function from the console
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a <- 1
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r <- renderTriple({ a * 10 })
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a <- 2
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r()
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# [1] "20, 20, 20"
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}
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\seealso{
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\code{\link[=quoToFunction]{quoToFunction()}}, \code{\link[=markRenderFunction]{markRenderFunction()}}, \code{\link[rlang:nse-defuse]{rlang::enquo()}}.
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}
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