export merge.data.table method (#3588)

NAMESPACE

@@ -87,6 +87,7 @@ S3method("names<-", data.table)
 S3method(duplicated, data.table)
 S3method(unique, data.table)
 S3method(merge, data.table)
+export(merge.data.table) #2618
 S3method(subset, data.table)
 S3method(transform, data.table)
 S3method(within, data.table)

NEWS.md

@@ -82,6 +82,8 @@
 
 11. `as.data.table` gains `key` argument mirroring its use in `setDT` and `data.table`, [#890](https://github.com/Rdatatable/data.table/issues/890). As a byproduct, the arguments of `as.data.table.array` have changed order, which could affect code relying on positional arguments to this method. Thanks @cooldome for the suggestion and @MichaelChirico for implementation.
 
+12. `merge.data.table` is now exported, [#2618](https://github.com/Rdatatable/data.table/pull/2618). We realize that S3 methods should not ordinarily be exported. Rather, the method should be invoked via S3 dispatch. But users continue to request its export, perhaps because of intracies relating to the fact that data.table inherits from data.frame, there are two arguments to `merge()` but S3 dispatch applies just to the first, and a desire to explicitly call `data.table::merge.data.table` from package code. Thanks to @AndreMikulec for the most recent request.
+
 #### BUG FIXES
 
 1. `first`, `last`, `head` and `tail` by group no longer error in some cases, [#2030](https://github.com/Rdatatable/data.table/issues/2030) [#3462](https://github.com/Rdatatable/data.table/issues/3462). Thanks to @franknarf1 for reporting.