knitr (version 1.18)

engine_output: An output wrapper for language engine output

Description

If you have designed a language engine, you may call this function in the end to format and return the text output from your engine.

Usage

engine_output(options, code, out, extra = NULL)

Arguments

options

a list of chunk options (usually this is just the object options passed to the engine function; see knit_engines)

code

the source code of the chunk, to which the output hook source is applied, unless the chunk option echo == FALSE

out

the text output from the engine, to which the hook output is applied, unless the chunk option results == 'hide'

extra

any additional text output that you want to include

Value

A character string generated from the source code and output using the appropriate output hooks.

Details

For expert users, an advanced usage of this function is engine_output(options, out = LIST) where LIST is a list that has the same structure as the output of evaluate::evaluate(). In this case, the arguments code and extra are ignored, and the list is passed to an internal function knitr:::wrap() to return a character vector of final output.

Examples

Run this code
# NOT RUN {
library(knitr)
engine_output(opts_chunk$merge(list(engine = "Rscript")), 
    code = "1 + 1", out = "[1] 2")
engine_output(opts_chunk$merge(list(echo = FALSE, engine = "Rscript")), 
    code = "1 + 1", out = "[1] 2")

# expert use only
engine_output(opts_chunk$merge(list(engine = "python")), 
    out = list(structure(list(src = "1 + 1"), class = "source"), 
        "2"))
# }

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