NEWS entry

NEWS.md

@@ -115,7 +115,9 @@ rowwiseDT(
 
 14. Added a `data.frame` method for `format_list_item()` to fix error printing data.tables with columns containing 1-column data.frames, [#6592](https://github.com/Rdatatable/data.table/issues/6592). Thanks to @r2evans for the bug report and fix.
 
-15. The auto-printing suppression in `knitr` documents is now done by implementing a method for `knit_print` instead of looking up the call stack, [#6589](https://github.com/Rdatatable/data.table/pull/6589). Thanks to @jangorecki for the report [#6509](https://github.com/Rdatatable/data.table/issues/6509) and @aitap for the fix.
+15. Auto-printing gets some substantial improvements
+   - Suppression in `knitr` documents is now done by implementing a method for `knit_print` instead of looking up the call stack, [#6589](https://github.com/Rdatatable/data.table/pull/6589). The old way was fragile and wound up broken by some implementation changes in {knitr}. Thanks to @jangorecki for the report [#6509](https://github.com/Rdatatable/data.table/issues/6509) and @aitap for the fix.
+   - `print()` methods for S3 subclasses of data.table (e.g. an object of class `c("my.table", "data.table", "data.frame")`) no longer print where plain data.tables wouldn't, e.g. `myDT[, y := 2]`, [#3029](https://github.com/Rdatatable/data.table/issues/3029). The improved detection of auto-printing scenarios has the added benefit of _allowing_ print in highly explicit statements like `print(DT[, y := 2])`, obviating our recommendation since v1.9.6 to append `[]` to signal "please print me".
 
 ## NOTES