Depth-first search

        sub AUTOLOAD {
          …
          my @stack = ($bottom_class);
          while (@stack) {
            my $class = pop @stack;
    
            next if $class eq __PACKAGE__;

• __PACKAGE__ is a compile-time constant for Help itself

            my $isa_var = $class . "::ISA";    
            push @stack, @{$isa_var};

            my $symbol_table = $class . "::";    
            for my $name (keys %{$symbol_table}) {
              my $func_name = $class . "::" . $name;
              next unless defined &{$func_name};
              $known_method{$name} ||= $class;
            }
          }

• %Horrible::Thing:: is the symbol table for the class

• It maps names to “globs” (don't ask)

• defined &{Horrible::Thing::fgsfds} asks if there is a function with that name

• Why &? (don't ask)

         …
       }
         

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