- my $val = $self->{$field};
- return $val if defined $val;
-
- my $mime = $self->{mime} or return;
- my @raw = $mime->header($field);
- $val = join(', ', @raw);
- $val =~ tr/\t\n/ /;
- $val =~ tr/\r//d;
- $self->{$field} = $val;
+ $self->{lc($field)} //= do {
+ my $mime = $self->{mime} or return;
+ my $val = join(', ', $mime->header($field));
+ $val =~ tr/\r//d;
+ $val =~ tr/\t\n/ /;
+ $val;
+ };