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a0bd9b5 Mar 21, 2017
@wch @yihui @jcheng5 @bborgesr
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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/shinywrappers.R
\name{renderPrint}
\alias{renderPrint}
\title{Printable Output}
\usage{
renderPrint(expr, env = parent.frame(), quoted = FALSE,
width = getOption("width"), outputArgs = list())
}
\arguments{
\item{expr}{An expression that may print output and/or return a printable R
object.}
\item{env}{The environment in which to evaluate \code{expr}.}
\item{quoted}{Is \code{expr} a quoted expression (with \code{quote()})? This
is useful if you want to save an expression in a variable.}
\item{width}{The value for \code{\link[base]{options}('width')}.}
\item{outputArgs}{A list of arguments to be passed through to the implicit
call to \code{\link{verbatimTextOutput}} when \code{renderPrint} is used
in an interactive R Markdown document.}
}
\description{
Makes a reactive version of the given function that captures any printed
output, and also captures its printable result (unless
\code{\link[base]{invisible}}), into a string. The resulting function is suitable
for assigning to an \code{output} slot.
}
\details{
The corresponding HTML output tag can be anything (though \code{pre} is
recommended if you need a monospace font and whitespace preserved) and should
have the CSS class name \code{shiny-text-output}.
The result of executing \code{func} will be printed inside a
\code{\link[utils]{capture.output}} call.
Note that unlike most other Shiny output functions, if the given function
returns \code{NULL} then \code{NULL} will actually be visible in the output.
To display nothing, make your function return \code{\link[base]{invisible}()}.
}
\examples{
isolate({
# renderPrint captures any print output, converts it to a string, and
# returns it
visFun <- renderPrint({ "foo" })
visFun()
# '[1] "foo"'
invisFun <- renderPrint({ invisible("foo") })
invisFun()
# ''
multiprintFun <- renderPrint({
print("foo");
"bar"
})
multiprintFun()
# '[1] "foo"\\n[1] "bar"'
nullFun <- renderPrint({ NULL })
nullFun()
# 'NULL'
invisNullFun <- renderPrint({ invisible(NULL) })
invisNullFun()
# ''
vecFun <- renderPrint({ 1:5 })
vecFun()
# '[1] 1 2 3 4 5'
# Contrast with renderText, which takes the value returned from the function
# and uses cat() to convert it to a string
visFun <- renderText({ "foo" })
visFun()
# 'foo'
invisFun <- renderText({ invisible("foo") })
invisFun()
# 'foo'
multiprintFun <- renderText({
print("foo");
"bar"
})
multiprintFun()
# 'bar'
nullFun <- renderText({ NULL })
nullFun()
# ''
invisNullFun <- renderText({ invisible(NULL) })
invisNullFun()
# ''
vecFun <- renderText({ 1:5 })
vecFun()
# '1 2 3 4 5'
})
}
\seealso{
\code{\link{renderText}} for displaying the value returned from a
function, instead of the printed output.
}