perl/env.pm

   1 package reader;
   2 use feature qw(switch);
   3 use strict;
   4 use warnings;
   5 use Exporter 'import';
   6
   7 use Data::Dumper;
   8
   9 {
  10     package Env;
  11     sub new  {
  12         my ($class,$outer,$binds,$exprs) = @_;
  13         my $data = { __outer__ => $outer };
  14         bless $data => $class
  15     }
  16     sub find {
  17         my ($self, $key) = @_;
  18         if (exists $self->{$key}) { return $self; }
  19         elsif ($self->{__outer__}) { return $self->{__outer__}->find($key); }
  20         else { return undef; }
  21     }
  22     sub set {
  23         my ($self, $key, $value) = @_;
  24         $self->{$key} = $value;
  25         return $value
  26     }
  27     sub get {
  28         my ($self, $key) = @_;
  29         my $env = $self->find($key);
  30         die "'" . $key . "' not found" unless $env;
  31         return $env->{$key};
  32     }
  33 }
  34
  35 #my $e1 = Env->new();
  36 #print Dumper($e1);
  37 #
  38 #my $e2 = Env->new();
  39 #$e2->set('abc', 123);
  40 #$e2->set('def', 456);
  41 #print Dumper($e2);
  42 #
  43 #my $e3 = Env->new($e2);
  44 #$e3->set('abc', 789);
  45 #$e3->set('ghi', 1024);
  46 #print Dumper($e3);
  47 #
  48 #print Dumper($e3->find('abc'));
  49 #print Dumper($e3->get('abc'));
  50 #print Dumper($e3->find('def'));
  51 #print Dumper($e3->get('def'));
  52
  53 1;