R: A simple macro preprocessor for templating purposes

knit_expand {knitr} | R Documentation

## A simple macro preprocessor for templating purposes

### Description

This function expands a template based on the R expressions in `{{}}` (this tag can be customized by the `delim` argument). These expressions are extracted, evaluated and replaced by their values in the original template.

### Usage

    knit_expand(file, ..., text = readLines(file, warn = FALSE), delim = c("{{", "}}"))

### Arguments

`file` | The template file.
`...` | A list of variables to be used for the code in the template; note that the variables will be searched for in the parent frame as well.
`text` | Character vector of lines of code. An alternative way to specify the template code directly. If `text` is provided, `file` will be ignored.
`delim` | A pair of opening and closing delimiters for the templating tags.

### Value

A character vector, with the tags evaluated and replaced by their values.

### References

This function was inspired by the pyexpander and m4 (http://www.gnu.org/software/m4/), thanks to Frank Harrell.

### Examples

    # see the knit_expand vignette
    if (interactive()) browseVignettes(package = "knitr")

[Package knitr version 1.20 Index]