eval, evaluate captures
all of the information necessary to recreate the output
as if you had copied and pasted the code into a R
terminal. It captures messages, warnings, errors and
output, all correctly interleaved in the order in which
they occured. It stores the final result, whether or not
it should be visible, and the contents of the current
graphics device.evaluate(input, envir = parent.frame(), enclos = NULL,
debug = FALSE)envir is a list or data frame,
this is treated as the parent environment to
envir.TRUE, displays information useful
for debugging, including all output that evaluate
captures