add helpful warning when trying to use $msg argument with LoggerGlue

Author: s-fleck

R/Logger.R

@@ -883,20 +883,33 @@ LoggerGlue <- R6::R6Class(
         )
 
         dots <- list(...)
-        sel <- names(dots) == ""
+
+        if ("msg" %in% names(dots)){
+          warning(
+            "LoggerGlue does not support a `$msg` argument. Please use unnamed ",
+            "text strings for construction your message like in `glue::glue()`.",
+            call. = FALSE
+          )
+          names(dots)[names(dots) == "msg"] <- ""
+        }
+
+        # construct msg
+        dots_msg <- dots  # because we need the original dots later again
+
+        sel <- names(dots_msg) == ""
         if (!length(sel)){
-          sel <- seq_along(dots)
+          sel <- seq_along(dots_msg)
         }
 
-        dots[sel] <- lapply(dots[sel], function(e){
+        dots_msg[sel] <- lapply(dots_msg[sel], function(e){
           if (inherits(e, "condition")){
             conditionMessage(e)
           } else {
             as.character(e)
           }
         })
 
-        msg <- do.call(glue::glue, args = c(dots, list(.envir = .envir)))
+        msg <- do.call(glue::glue, args = c(dots_msg, list(.envir = .envir)))
 
         # Check if LogEvent should be created
         if (
@@ -909,15 +922,8 @@ LoggerGlue <- R6::R6Class(
         force(caller)
 
         if (missing(...)){
-          vals <- list(
-            logger = self,
-            level = level,
-            timestamp = timestamp,
-            caller = caller,
-            msg = msg
-          )
+          stop("No log message or structured logging fields supplied")
         } else {
-          dots <- list(...)
           custom_fields <- !(grepl("^\\.", names(dots)) | is_blank(names(dots)))
 
           vals <- c(

tests/testthat/test_Logger.R

@@ -428,6 +428,11 @@ test_that("Appender error contains useful call object", {
   l <- get_logger("test")$set_propagate(FALSE)
   g <- get_logger_glue("testglue")$set_propagate(FALSE)
 
+  on.exit({
+    l$config(NULL)
+    g$config(NULL)
+  })
+
   AppenderFail <- R6::R6Class(
     "AppenderFail",
     inherit = Appender,
@@ -445,3 +450,19 @@ test_that("Appender error contains useful call object", {
   expect_warning(g$info("this will fail"), ".*AppenderFail.*g\\$info")
 })
 
+
+
+
+
+test_that("Logger$log 'msg' argument works as expected", {
+  l <- get_logger("test")$set_propagate(FALSE)
+  g <- get_logger_glue("testglue")$set_propagate(FALSE)
+
+  on.exit({
+    l$config(NULL)
+    g$config(NULL)
+  })
+
+  expect_silent(l$log(level = "fatal", msg = "test"))
+  expect_warning(g$log(level = "fatal", msg = "test"), "does not support")
+})