Accessors are dangerous

So commonly used accessors (setters/getters) I think are dangerous when overused or used without a caution. Here is a quick list why.

• Too many accessors are a sign of a class that does too much or is highly coupled
• Too much information is revealed about the class
• Accessors that have the same name for setting and getting variables may be confused with normal methods since they don't state clearly if they are read only

      $invoice->price(100); # Nothing happens
      $invoice->price;      # Anything but 100

• Encourage breaking of Tell Dont Ask and Law of Demeter principles

      if ($invoice->price > 100) {
          $invoice->pay;
      }

• Require too much of configuration when more advanced behaviour is needed

      has 'book' => sub {
  
          # Setter
          if (@_) {
              my $value = shift;
  
              if ($value =~ m/.../) {
                  ...
              }
  
              return;
          }
  
          # Getter
      };

• Trying to be universal add a lot of checks that are not always needed
• Too many ways to do it

      Class::MethodMaker
      Object::Tiny
      Spiffy
      Class::Spiffy
      accessors
      Object::Tiny
      Rubyish::Attribute 
      Class::Accessor
      Class::Accessor::Fast
      Class::Accessor::Complex
      Class::Accessor::Constructor
      Class::Accessor::Classy
      Class::Accessor::Lite 
      Class::XSAccessor 
      Moose
      Mouse
      Moo
      Mo

  and

      Mojo::Base::XS # yeah, baby, yeah!

  See also App::Benchmark::Accessors.

• Are slow and require optimization magic (literally)

  See Class::XSAccessor

  For me it's not difficult to write 3-5 methods that set/get variables while keeping encapsulation and ease of modification (though I must admit I have CPAN modules that do not follow this approach, but the time will come!).