R/history.R

In histry: Enhanced Command History Tracking for R Sessions and Dynamic Documents

#' @title Construct and activate a HistoryTracker object
#' @description Constructors for the HistoryTrackr family of objects.
#' @note Generally end-users should never need to call these functions directly. Simply
#' loading the histry package should provide them with history tracking.
#' @param id character. The id of the taskback
#' @return A HistoryTracker object
#' @rdname tracker-constructors
#' @export
historyTracker = function(id = "history_tracker") {
    h_tracker$new(id = id)
}

#' @rdname tracker-constructors
#' @aliases knitr_tracker
#' @export
knitrTracker = function() {
    if(!requireNamespace("knitr", quietly=TRUE))
        return(NULL)
    kh_tracker$new()
}

setMethod("show", "VirtHistoryTracker",
          function(object) {

    if(is.language(exprs(object)) && length(exprs(object)) >0)
        msg = deparse(exprs(object))
    else if (length(exprs(object)) > 1)
        msg = paste(tail(exprs(object),5), collapse="\n")
    else
        msg = "No messages in history record"
    cat("A history tracker of class", class(object), "\nRecent expressions:",
        msg, "\n(For full history do exprs(obj))\n")
})