The R Project SVN R

    ##================================================================##
    ###  In longer simulations, aka computer experiments,        ###
    ###  you may want to                         ###
    ###  1) catch all errors and warnings (and continue)         ###
    ###  2) store the error or warning messages          ###
    ###                              ###
    ###  Here's a solution  (see R-help mailing list, Dec 9, 2010):  ###
    ##================================================================##

##' Catch *and* save both errors and warnings, and in the case of
##' a warning, also keep the computed result.
##'
##' @title tryCatch both warnings (with value) and errors
##' @param expr an \R expression to evaluate
##' @return a list with 'value' and 'warning', where
##'   'value' may be an error caught.
##' @author Martin Maechler;
##' Copyright (C) 2010-2012  The R Core Team
tryCatch.W.E <- function(expr)
{
    W <- NULL
    w.handler <- function(w){ # warning handler
    W <<- w
    invokeRestart("muffleWarning")
    }
    list(value = withCallingHandlers(tryCatch(expr, error = function(e) e),
                     warning = w.handler),
     warning = W)
}

str( tryCatch.W.E( log( 2 ) ) )
str( tryCatch.W.E( log( -1) ) )
str( tryCatch.W.E( log("a") ) )