composite pattern, best practice, pushing into an array in a hash, reusing the get array method

gargle has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I'm a bit puzzled... :( I have implemented a composite pattern and wanted to reuse a sub called getCreditAccounts() I have already written down.

getBalansCreditAmount() calls all accounts in the CREDITACCOUNTS array and reapplies itself to get the credit amounts stored there. getCreditAccounts(), used by getBalansCreditAmount() returns an array with accounts. (the sub is listed below)

I also have a addCreditAcount() to add accounts to the CREDITACCOUNTS array. In this sub I first fetch the parameter, a new account. Then I want to get the contents of CREDITACCOUNTS and push the new account in it. I do this byy taking the reference from &{ $closure }("CREDITACCOUNTS") in an $accountref and pushing the new account in the de-reference.(the sub is listed below)

However, I feel like I didn't reuse getCreditAccounts() because of the funny looking my $accountsref = &{ $closure }("CREDITACCOUNTS")

my constructor

sub new {
    my $class = shift;
    my $name  = shift;
    my $self  = {
        NAME           => $name,
        CREDITAMOUNT   => Math::BigInt->new(0),
        DEBETAMOUNT    => Math::BigInt->new(0),
        CREDITACCOUNTS => [],
        DEBETACCOUNTS  => [],
    };
    my $closure = sub {
        my $field = shift;
        if (@_) { $self->{$field} = shift; }
        return $self->{$field};
    };
    bless( $closure, $class );
    return $closure;
}
[download]

addCreditAccount()

# public to add accounts to the creditaccounts
sub addCreditAccount {
    my $closure  = shift;
    my $account = shift;
    my $accountsref = &{$closure}( "CREDITACCOUNTS" );
    push @{ $accountsref }, $account;
}
[download]

getBalansCreditAmount()

# public getBalansCreditAmount to get the amount of all accounts
sub getBalansCreditAmount {
    my $closure = shift;
    my $totalCreditAmount = $closure->getCreditAmount();
    for my $balans ( $closure->getCreditAccounts() ) {
        $totalCreditAmount += $balans->getBalansCreditAmount();
    }
    return $totalCreditAmount;
}
[download]

getCreditAccounts()

# private getCreditAccounts
sub getCreditAccounts {
    caller(0) eq __PACKAGE__ || confess "getCreditAccounts is private"
+;
    my $closure = shift;
    my @accounts = @{ &{$closure}( "CREDITACCOUNTS" ) };
    return @accounts;
}
[download]

A a lot of retyping seems to just have happened. Is there a way to reuse getCreditAccounts() in the addCreditAccount sub to make the code a bit clearer to understand?

ps: I need to check for circular references in this code. This I'll implement this later!

--
if ( 1 ) { $postman->ring() for (1..2); }

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Re: composite pattern, best practice, pushing into an array in a hash, reusing the get array method by vladb (Vicar) on Feb 13, 2006 at 21:23 UTC
To reuse `getCreditAccounts()`, you'd have to first rewrite the method to return array ref, and not a copy of the array you are attempting to ultimately change. `# private getCreditAccounts sub getCreditAccounts { caller(0) eq __PACKAGE__ \|\| confess "getCreditAccounts is private" +; my $closure = shift; my @accounts = @{ &{$closure}( "CREDITACCOUNTS" ) }; return @accounts; } # working on a copy of the original array... my @anotherArray = $obj->getCreditAccounts(); push @anotherArray, "Data";` [download] From there, you could possibly do something like `# private getCreditAccounts # now returning reference to the original array sub getCreditAccounts { caller(0) eq __PACKAGE__ \|\| confess "getCreditAccounts is private" +; my $closure = shift; return &{$closure}( "CREDITACCOUNTS" ) }; } # public to add accounts to the creditaccounts sub addCreditAccount { my $closure = shift; my $account = shift; push @{ $closure->getCreditAccounts() }, $account; }` [download] _____________________ "We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true." Robert Wilensky, University of California	[reply] [d/l] [select]

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Re: composite pattern, best practice, pushing into an array in a hash, reusing the get array method
by vladb (Vicar) on Feb 13, 2006 at 21:23 UTC

getCreditAccounts()

# private getCreditAccounts
sub getCreditAccounts {
    caller(0) eq __PACKAGE__ || confess "getCreditAccounts is private"
+;
    my $closure = shift;
    my @accounts = @{ &{$closure}( "CREDITACCOUNTS" ) };
    return @accounts;
}

# working on a copy of the original array...
my @anotherArray = $obj->getCreditAccounts();
push @anotherArray, "Data";
[download]

# private getCreditAccounts
# now returning reference to the original array
sub getCreditAccounts {
    caller(0) eq __PACKAGE__ || confess "getCreditAccounts is private"
+;
    my $closure = shift;
    return &{$closure}( "CREDITACCOUNTS" ) };
}

# public to add accounts to the creditaccounts
sub addCreditAccount {
    my $closure  = shift;
    my $account = shift;
    push @{ $closure->getCreditAccounts() }, $account;
}
[download]

_____________________
"We've all heard that a million monkeys banging on a million typewriters will eventually reproduce
the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true."

Robert Wilensky, University of California

[reply]
[d/l]
[select]