Matt's Notes

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======Extensions to the R brew Package======
=====Literal Evaluation=====
The code below may be passed as the ''tplParser'' argument to the ''brew'' function in the ''brew'' package by Jeff Horner. ''brewLiteral'' does something similar to Sweave, by echoing the evaluated code, and printing the results.
<code c brewLiteral.R>
brewLiteral <- function(code) {
    out <- ""
    exp <- try(parse(text=code),TRUE)
    if(inherits(exp, "try-error"))
        return(exp)
    for(i in 1:length(exp)) {
        dep <- deparse(exp[[i]])
        for(j in 1:length(dep)) {
            pmt <- ifelse(j > 1, 
                getOption("continue"),
                getOption("prompt"))
            out <- paste(out, pmt, dep[j], "\n", sep="")
        }
	res <- try(capture.output(eval(exp[i])),TRUE)
	if(length(res)>0 && !grepl("^.*\\n$", res))
            res <- paste(res, "\n")
        out <- paste(out, res, sep="")
    }
    return(out)
}
</code>

=====Problems=====
  * ''tplParser'' is not evaluated in the cumulative ''brew'' environment
  * ''brew'' doesn't always close the input connection (Warning message: closing unused connection)
=====Ideas=====
  * allow brew to accept additional, or generic delimiters of the form '<%?' and '%>'
  * allow the user to specify actions for additional delimiters //a la// ''tplParser''

Matt's Notes

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