19 BankAccount->meta->add_attribute(
21 accessor => 'balance',
22 init_arg => 'balance',
27 sub new { (shift)->meta->new_object(@_) }
30 my ( $self, $amount ) = @_;
31 $self->balance( $self->balance + $amount );
35 my ( $self, $amount ) = @_;
36 my $current_balance = $self->balance();
37 ( $current_balance >= $amount )
38 || confess "Account overdrawn";
39 $self->balance( $current_balance - $amount );
42 package CheckingAccount;
48 use base 'BankAccount';
50 CheckingAccount->meta->add_attribute(
51 'overdraft_account' => (
52 accessor => 'overdraft_account',
53 init_arg => 'overdraft',
57 CheckingAccount->meta->add_before_method_modifier(
59 my ( $self, $amount ) = @_;
60 my $overdraft_amount = $amount - $self->balance();
61 if ( $overdraft_amount > 0 ) {
62 $self->overdraft_account->withdraw($overdraft_amount);
63 $self->deposit($overdraft_amount);
70 CheckingAccount->meta->add_before_method_modifier(
71 'does_not_exist' => sub { } );
73 qr/\QThe method 'does_not_exist' was not found in the inheritance hierarchy for CheckingAccount/
76 ::ok( CheckingAccount->meta->has_method('withdraw'),
77 '... checking account now has a withdraw method' );
78 ::isa_ok( CheckingAccount->meta->get_method('withdraw'),
79 'Class::MOP::Method::Wrapped' );
80 ::isa_ok( BankAccount->meta->get_method('withdraw'),
81 'Class::MOP::Method' );
83 CheckingAccount->meta->add_method( foo => sub { 'foo' } );
84 CheckingAccount->meta->add_before_method_modifier( foo => sub { 'wrapped' } );
85 ::isa_ok( CheckingAccount->meta->get_method('foo'),
86 'Class::MOP::Method::Wrapped' );
89 my $savings_account = BankAccount->new( balance => 250 );
90 isa_ok( $savings_account, 'BankAccount' );
92 is( $savings_account->balance, 250, '... got the right savings balance' );
94 $savings_account->withdraw(50);
96 '... withdrew from savings successfully';
97 is( $savings_account->balance, 200,
98 '... got the right savings balance after withdrawal' );
100 $savings_account->withdraw(250);
102 '... could not withdraw from savings successfully';
104 $savings_account->deposit(150);
105 is( $savings_account->balance, 350,
106 '... got the right savings balance after deposit' );
108 my $checking_account = CheckingAccount->new(
110 overdraft => $savings_account
112 isa_ok( $checking_account, 'CheckingAccount' );
113 isa_ok( $checking_account, 'BankAccount' );
115 is( $checking_account->overdraft_account, $savings_account,
116 '... got the right overdraft account' );
118 is( $checking_account->balance, 100, '... got the right checkings balance' );
121 $checking_account->withdraw(50);
123 '... withdrew from checking successfully';
124 is( $checking_account->balance, 50,
125 '... got the right checkings balance after withdrawal' );
126 is( $savings_account->balance, 350,
127 '... got the right savings balance after checking withdrawal (no overdraft)'
131 $checking_account->withdraw(200);
133 '... withdrew from checking successfully';
134 is( $checking_account->balance, 0,
135 '... got the right checkings balance after withdrawal' );
136 is( $savings_account->balance, 200,
137 '... got the right savings balance after overdraft withdrawal' );