You cannot sort by a bare anonymous sub. See sort:

sort SUBNAME LIST
sort BLOCK LIST
sort LIST

sort wants a BLOCK or a named sub.

But you can do either of

        for my $rec ( sort { $sortby->() } @{$dns_records{$_}} ) {

[download]

and

        local *sortby = setsort($_);
        for my $rec ( sort sortby @{$dns_records{$_}} ) {

[download]

As for the error message: 

Array found where operator expected at ./sample.pl line 5, at end of l
+ine
        (Missing operator before ?)

[download]

- this means that sort treats the anonsub as pertinent to the items to be sorted, and perl complains about the missing comma between the sub and the following array.

In reply to Re: Syntax question about closures and Perl 'sort' by shmem
in thread Syntax question about closures and Perl 'sort' by dwm042

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