R/logging.R

In shambam/cellexalvrR: Provides the backend calculations for CellexalVR

##https://stackoverflow.com/questions/33556266/logging-console-history-with-errors-in-r-or-rstudio
##https://stackoverflow.com/questions/17710469/why-wont-cat-append-to-a-file-connection
# error handler
logErr <- function() {
	# turn logging callback off while we process errors separately
	tcbm$suspend(TRUE)
	# turn them back on when we're done
	on.exit(tcbm$suspend(FALSE))
	sc <- sys.calls()
	sclen <- length(sc)  # last call is this function call
	if(sclen > 1L) {
		if ( file.exists( "logfile.R") ) {
			cattest <- file("logfile.R", open = "a")
		}else {
			cattest <- file("logfile.R" )
		}
		cat("myError:\n", do.call(paste, c(lapply(sc[-sclen], deparse), sep="\n")), "\n", file=cattest, append=T)
	} else {
		# syntax error, so no call stack
		# show the last line entered
		# (this won't be helpful if it's a parse error in a function)
		file1 <- tempfile("Rrawhist")
		savehistory(file1)
		rawhist <- readLines(file1)
		unlink(file1)
		if ( file.exists( "logfile.R") ) {
			cattest <- file("logfile.R", open = "a")
		}else {
			cattest <- file("logfile.R" )
		}
		cat("myError:\n", rawhist[length(rawhist)], "\n", file=cattest, append=T)
	}
}
options(error=logErr)
# top-level callback handler
log <- function(expr, value, ok, visible) {
	if ( file.exists( "logfile.R") ) {
		cattest <- file("logfile.R", open = "a")
	}else {
		cattest <- file("logfile.R" )
	}
	cat(deparse(expr), "\n", file=cattest, append=T)
	TRUE
}
tcbm <- taskCallbackManager()
tcbm$add(log, name = "log")