develooper Front page | perl.perl5.porters | Postings from April 2000

'=' in Overload Question

April 20, 2000 06:44
'=' in Overload Question
Message ID:
I have a question regarding the Overload module and why the '=' does not
overload the assignment operator.  There is mention that this would 'rub the
Camel hair the wrong way' but not why Tie is allowed to do that exact thing.

I would like to bless an object and then have the option of overloading the
assigment operator so that I could do something like this:

$mydate = Datatype::Date->new();
$mydate = '12/31/98';   # Does not alter $mydate's bless'dness
print $mydate;      # prints Dec-31-1998

Tie'd objects get the STORE method where they can interpret the incoming data in
the appropriate way for that object.  Why is this not available to Overload?  If
I go to the effort of blessing an object into a class, why can't I decide for
myself whether I want to let Perl trump my blessing and stomp on my object? 
Obviously if I do not chose to overload the assignment, the fallback would be
the current behavior.

The example above is obviously trivial; what I really want to do is tag several
scalars as special and then assign to a group of scalars from a DBI query all at
once.  With the existing code, I need to re-bless each special scalar after the
assignment (this is actual code):

( $po_number, $original_amt, $discount_1, $payments, $credit_amt,
$last_pay_date, $transaction_dt, $closed ) = $COI->fetchrow_array;

$original_amt   = Money($original_amt);
$discount_1     = Money($discount_1);
$payments       = Money($payments);
$credit_amt     = Money($credit_amt);
$last_pay_date  = Date($last_pay_date);
$transaction_dt = Date($transaction_dt);

Please enlighten me as to the error of my ways, or point me at a FAQ that might
cover this.

Thanks in Advance

John Peacock Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About