R: An output wrapper for language engine output

engine_output {knitr} | R Documentation

## 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` | Source code of the chunk, to which the output hook `source` is applied, unless the chunk option `echo` is `FALSE`.
`out` | Text output from the engine, to which the hook `output` is applied, unless the chunk option `results` is `'hide'`
`extra` | Any additional text output that you want to include.

### 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.

### Value

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

### Examples

    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"))

[Package knitr version 1.20 Index]