Current overview

  load all items into array of hash
  for each input item {
    complex transformation rules 
  }
  save all items (timestamped)
  remove all items with old timestamp
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Some alternatives I am testing for the loop:

OUTER-IF:
  if ( $type eq 'apple' ) {
    for my $item ( @items ) {
      apple_wash($item);
      apple_core($item);
      apple_pulp($item);
    }
  } elsif ( $type eq 'banana') {
    for my $item ( @items ) {
      banana_bend($item);
      banana_hang($item);
    }
  } else {
    die "bad fruit: $type";
  }

INNER-IF:
  for my $item ( @items ) {
    if ( $type eq 'apple' ) {
      apple_wash($item);
      apple_core($item);
      apple_pulp($item);
    } elsif ( $type eq 'banana') {
      banana_bend($item);
      banana_hang($item);
    } else {
      die "bad fruit: $type";
    }
  }

ARRAY OF SUB-REF:
  my @funcs;
  if ( $type eq 'apple' ) {
    push @funcs, \&apple_wash, \&apple_core, \&apple_pulp;
  } elsif ($type eq 'bananas') {
    push @funcs, \&banana_bend, \&banana_hang;
  } else {
    die "bad fruit: $type";
  }
  for my $item ( @items ) {
    for my $func (@funcs) {
      $func->($item);
    }
  }

SYMBOL-TABLE FIDDLE:
  if ( $type eq 'apple' ) {
    *func1 = \&apple_wash;
    *func2 = \&apple_core;
    *func3 = \&apple_pulp;
  } elsif ($type eq 'bananas') {
    *func1 = \&banana_bend;
    *func2 = \&banana_hang;
    *func3 = \&noop;
  } else {
    die "bad fruit: $type";
  }
  for my $item ( @items ) {
    func1($item) unless \&func1 == \&noop;
    func2($item) unless \&func2 == \&noop;
    func3($item) unless \&func3 == \&noop;
  }
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Specifics: I have profiled some test code with these four approaches -

OUTER-IF is the (slightly) fastest, but unwieldy in the real instance, as there are hundreds of infrastructural lines omitted from the example that make if hard to maintain duplicate FOR LOOPs.

INNER-IF is also fast, but results in difficult to maintain and long... code inside the FOR LOOP

ARRAY OF SUB-REF: slower than IFs - must be cost of dereferencing the function ref? but makes huge FOR LOOP mucho clearer.

SYMBOL-TABLE FIDDLE: I am a symbol-table virgin, and my symbol-table stuff looks poor - are there better sym-t syntacies? Generates 'Redefined function XXX' warnings.