I've been learning a little about Discrete Finite Automata and I'm excited about using them for lexing mathematical expressions. I have a question about why the following code seems to work.

sub argout {
    my $temp = {'type'=>'ARG',
                'value'=>$buffer};
    $buffer = '';
    push(@output,$temp);
}
sub otherout {
   my $c = shift;
   my $temp = {'type'=>'OTHER',
               'value'=>$c};
   push(@output,$temp);
}

%states = (
'start'=>{'s'=>{'nextstate'=>'var1.1'}},

'var1.1'=>{'i'=>{'nextstate'=>'var1.2'}},

'var1.2'=>{'s'=>{'action'=>'argout',
                 'nextstate'=>'var1.1'},
           'eof'=>{'action'=>'argout'}}
);
  
sub lex {
   my $inputstring = shift;
   my @input = split('',$inputstring);
   my @output = ();
   $buffer = '';
   my $s = 'start';
   foreach my $c (@input,'eof') {
      if( my $t = $states{$s}->{$c} ) {
     eval( $t->{'action'} );
         $s = $t->{'nextstate'};
      }
      else {
         otherout($c);
         return 0;
      }
      $buffer = $buffer.$c;
   }
   return 1;
}

if( lex('sisisi') ) {
   print("success!\n");
}
else {print("failure...")} 
foreach my $tok (@output) {
   print("$tok->{'type'},$tok->{'value'}\n");
}
[download]

This code produces the following output.

success!
ARG,si
ARG,si
ARG,si
[download]

It seems to rely on the $buffer being a sort of "global" variable (global vars are bad right?), so that the argout function can access it. Now if I add a 'my' keyword in front of the $buffer declaration (inside the lex subroutine) then the output is the following.

success!
ARG,
ARG,
ARG,
[download]

Presumably this is because the $buffer variable is no longer accessible from the 'argout' subroutine. Why is the @output variable accessible from the 'argout' subroutine even though it is declared local to 'lex'?

Knowing this would be one thing, but what I really want is that the $buffer, the @input, the @output, and possibly even the $c would be data inside of a "Dfa" object, and all of those other methods could just access those variables whenever they wanted. The reason I haven't done this yet is that the only way I know how to make objects in Perl is to make sort of a "special hash" and bless it with functions that have intimate access to it. I didn't want to do this because I didn't want to have to use constructs like $self->{'buffer'} everytime I wanted to use the buffer variable. I feel like I'm still stuck in a sort of "Java Mode" of thinking right now...Is there a better, "Perler" way of doing all this?

Any help will be greatly appreciated,
~Terry

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