G'day...
Yeah, I should have used qw not qq, and after I sent it I thought "Why
didn't I just say keys %InheritableClassData instead.." :)
I'm trying to create a class that has data members which are the same
for all instances, including instances of derived classes, as well as
containing data members which exist in all instances, but values are
class dependent.
Considering that I've only more recently mastered the basics of
objects/classes in Perl - this is quite a daunting thing!
I've been reading through perltootc, but a lot of it goes straight over
the top of my head (or I only remember part of the concept Tom is
talking about).
I guess it means I just have to keep studying - although any help with
this task would be appreciated. :)
What I was trying to achieve with this:
--START--
: our %InheritableClassData = (
DBH => undef,
Q => undef,
Handler => undef,
);
foreach (qq(DBH Q Handler)) {
sub $_ {
shift;
$InheritableClassData{$_} = shift if @_;
return $InheritableClassData{$_};
}
}
---END---
Was really just an attempt at a shorthand version of:
--START--
: our %InheritableClassData = (
DBH => undef,
Q => undef,
Handler => undef,
);
sub DBH {
shift;
$InheritableClassData{DBH} = shift if @_;
return $InheritableClassData{DBH};
}
sub Q {
shift;
$InheritableClassData{Q} = shift if @_;
return $InheritableClassData{Q};
}
sub Handler {
shift;
$InheritableClassData{Handler} = shift if @_;
return $InheritableClassData{Handler};
}
---END---
Should I be using "my" or "our" here for the variables - these are the
variables I want present in all my derived classes and should be the
same for all.
Thanks heaps Charles, your help and assistance on this list is
appreciated by us all...
Regards,
Michael S. E. Kraus
Software Developer/Technical Support Specialist
Wild Technology Pty Ltd
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-----Original Message-----
From: Charles K. Clarkson [mailto:[EMAIL PROTECTED]
Sent: Wednesday, 17 November 2004 5:30 PM
To: [EMAIL PROTECTED]
Subject: Spam:RE: Autmatic function creation
Michael Kraus <[EMAIL PROTECTED]> wrote:
: Just wondering if this code snippet will behave as expected,
: and if not then why not? :)
No, I don't think so. One error is in using the qq() operator
instead of the qw() operator. Even with that fix, perl throws syntax
errors.
: --START--
: our %InheritableClassData = (
: DBH => undef,
: Q => undef,
: Handler => undef,
: );
:
: foreach (qq(DBH Q Handler)) {
: sub $_ {
: shift;
: $InheritableClassData{$_} = shift if @_;
: return $InheritableClassData{$_};
: }
: }
We could test solutions by examining the symbol table.
When creating new functions (or methods in an object), perl adds
entries to the symbol table (%::). If we store the keys previous to
setting the functions, we can delete() them from the table keys
afterward and find if any new symbols were added.
use Data::Dumper 'Dumper';
.
.
.
# store current symbol table keys
my @prev_keys = keys %::;
foreach my $method ( keys %InheritableClassData ) {
no strict 'refs';
*$method = sub {
shift;
$InheritableClassData{$_} = shift if @_;
return $InheritableClassData{$_};
};
}
# store current symbol table
my %new_table = %::;
# delete old keys
delete @new_table{ @prev_keys };
print
"Added symbol table entries\n",
Dumper \%new_table;
__END__
I get:
Added symbol table entries
$VAR1 = {
'Handler' => *::Handler,
'Q' => *::Q,
'DBH' => *::DBH
};
HTH,
Charles K. Clarkson
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