I found one solution using eval. Any additional comments are welcome: 
my $ordered_schema = sprintf(
    "%s%s",
    $header . "\n",
    eval {
        my $ordered_columns;
        for my $column (sort keys %columns) {
            $ordered_columns .= $columns{$column} . "\n";
        }
        return $ordered_columns;
    },
);

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In reply to Re: sprintf: using nested code by mhearse
in thread sprintf: using nested code by mhearse

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