package Object;
use vars '$AUTOLOAD';
# :
sub AUTOLOAD : lvalue
{
my ($self) = shift;
$AUTOLOAD =~ s/.*://;
@_? $self->{$AUTOLOAD} = shift : $self->{$AUTOLOAD} ||= undef;
}
Sweet candy.
Now you can do stuff like this:
my ($object) = new Object;
$object->whatever = "Data";
print "Whatever is '",$object->whatever,"'\n";
It "goes both ways" as an LVALUE, and this AUTOLOAD routine
has backwards compatibility with the older, somesay wacky
function method:
my ($object) = new Object;
$object->whatever("Data");
print "Whatever is '",$object->whatever(),"'\n";
You even get warnings with perl -w if you use
uninitialized members.
| [reply]
[d/l] |
That's twisted and clever. One question: what is the intent of the ||= undef, other than changing $self->{$AUTOLOAD} to undef if it's 0 or ""?
my ($object) = new Object;
$object->whatever(0);
print "Whatever is '",$object->whatever(),"'\n"; # Oops!
| [reply]
[d/l]
[select] |
chipmunk points out something that I
had failed to test for. In my effort to reduce the
code down to a minimum, that case slipped right through
my logic. Here's Take II, new and improved support for
0 and "" added:
sub AUTOLOAD : lvalue
{
my ($self) = shift;
$AUTOLOAD =~ s/.*://;
@_?
$self->{$AUTOLOAD} = shift
: !defined($self->{$AUTOLOAD})?
$self->{$AUTOLOAD} = undef
: $self->{$AUTOLOAD};
}
The reason for having $self->{$AUTOLOAD} = undef
is to give the caller something to assign to. Returning an
invalid hash entry will cause an assignment error. 'undef' is
not a valid lvalue, but returning a reference to a variable
which may have a value of 'undef' is acceptable.
BTW, I've never had to indent my '?:'s before, but it was the
only way to make how this worked clear(er). | [reply]
[d/l] |
Good example, but I think you mean shift :P
-Lee
"To be civilized is to deny one's nature." | [reply] |