Conditions have classes and the condition system is designed around the idea that classes would be used for this sort of thing. That is already how tryCatch and withCallingHandlers discriminate the conditions to handle.
Designing and implementing a condition class hierarchy to support this is indeed the hard/tedious part. Best, luke On Thu, 10 Sep 2015, Richard Cotton wrote:
The suppressMessages and suppressWarnings functions currently suppress all the message or warnings that are generated by the input expression. The ability to suppress only specific messages or warnings is sometimes useful, particularly for cases like file import where there are lots of things that can go wrong. Suppressing only messages that match a regular expression has rightly been rejected as problematic due to non-portability across locales. See, for example, https://stat.ethz.ch/pipermail/r-devel/2012-October/065089.html A better way of suppressing certain conditions would be to allow them to have an identifier. (This is how MATLAB allows control over individual conditions.) The implementation ought to be fairly simple. simpleMessage, simpleWarning, and simpleError gain an id arg, which is stored in their structure. simpleMessage <- function (message, call = NULL, id = NULL) { structure( list(message = message, call = call, id = id), class = c("simpleMessage", "message", "condition") ) } I envisage IDs being strings, for example, the "NaN produced" warning when you ask call, e.g., sqrt(-1) could have an ID of "base:sqrt:nan_produced". suppressMessage and suppressWarnings gain an ids arg, defaulting to NULL, which preserves existing behaviour. If it takes a character vector, messages with the IDs provided get muffled. Something like: suppressMessages <- function (expr, ids = NULL) { withCallingHandlers( expr, message = function(c) { if(is.null(ids) || (inherits(c, "simpleMessage") && c$id %in% as.character(ids))) { invokeRestart("muffleMessage") } } ) } The hard part is providing IDs for all the existing messages in R and its packages. It's certainly do-able, but I imagine would take quite a lot of time. Is there any enthusiasm for implementing this feature, or something like it?
-- Luke Tierney Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: luke-tier...@uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
