I would not recommend reading whole file into memory since you said it would be big binary file :) I would have classes for each type MainHeader, ExtensionHeader, PartOne, PartTwo, etc. Each class constructor would take binary data as parameter.

When you say each section has a field that knows length, does it mean it is Tag-Length-Value? https://en.wikipedia.org/wiki/Type-length-value in that case, you could have main loop in parser class and pass each record binary chunk(from length) to appropriate class based on tag.

Parser class would be something like iterable; where client invoke next()/ (or ->() in perl land) method to advance/get next record from file. 

#pseudo code 
# error handling omitted!

sub parser_factory {
   my $file_path = shift;
   my %options = @_;
   fh = open_file($file_path)

   my $iterator = sub {
   # closure ; flag end of data/closing file omitted
   while( header = read(fh)) {
      length = get_length(header)
      body = read(fh,length)
      type = get_type(header)
      class =get_record_class(header) # return class name
      return class->new(body);
   
    }
   }
   return $iterator
}

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In reply to Re: Best way to a parse a big binary file by pwagyi
in thread Best way to a parse a big binary file by Dirk80

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