add live 6

sose2021/r/w06/L06-1.R

@@ -0,0 +1,27 @@
+clear_warnings <- function() last.warning <<- list()
+
+careless <- function(f) {
+    function(...) {
+        suppressWarnings(f(...))
+    }
+}
+
+fail_with <- function(expr, value) tryCatch(expr, error = function(cond) value)
+does_error <- function(expr) {
+    didFail <- F
+    tryCatch(expr, error = function(cond) didFail <<- T)
+    didFail
+}
+
+count_warnings <- function(expr) {
+    N <- 0
+    withCallingHandlers(expr, warning = function(cond) N <<- N + 1)
+    N
+}
+
+record <- function(expr) {
+    msgs <- c()
+    rec <- function(cond) { msgs <<- c(msgs, cond$message); rlang::cnd_muffle(cond)}
+    withCallingHandlers(expr, warning = rec, message = rec)
+    msgs
+}