if(!identical(globalenv(), parent.frame()))

stop("'cc' must be called from the global environment")

subexpr <- substitute(expr)

exprtext <- deparse(subexpr, width.cutoff = 60)

if(is.null(srcfile))

srcfile <- file.path(tempdir(), hash(exprtext))

writeLines(exprtext, srcfile)

cacher(srcfile, cachedir, ...)

if(is.null(logfile)) {

logfile <- file.path(logdir(cachedir),

paste(basename(srcfile), "log", sep="."))

file.create(logfile)

}

else if(is.na(logfile))

logfile <- stderr()

else

file.create(logfile)

setConfig("logfile", logfile)

## Are the contents of the two files the same?

checksum <- c(hashFile(x), hashFile(y))

identical(checksum[1], checksum[2])