So, the solution to this is accessing data or setting it via methods . . . I've seen a getter/setter in OO tutorials, one written for each attribute.

Yes, most tutorials do it that way. They're wrong, or at least misleading. Getter/setter methods (or for those who like fancier words, accessors/mutators) should be avoided. Sometimes you do need them on a few attributes, but if your design calls for accessors/mutators on every internal attribute, you need to rethink your design. Doing it that way won't really result in an object, but a datastructure that happens to be accessed with an object-like syntax. The only difference between this:

$obj->{field};

[download]

And this:

$obj->field();

[download]

Is some fancy syntax. I bet the second form is slower, too (haven't benchmarked it, though).

Now when you actually do need accessors/mutators . . .

Why do you need a different method for each bit of data?

True to TIMTOWTDI, Perl offers many ways of producing accessors/mutators. Your way isn't necessarily wrong. If use strict 'subs'; was useful for method lookups, then I think you can make a stronger argument against what you're doing (since a method-per-attribute way would give you compile-time errors when you make a typo). Since methods are all looked up at run time, use strict 'subs'; isn't particularly useful no matter how you do it.

One problem with your way of generating accessors/mutators is that, unless you do checking inside the method, a user can insert an attribute that didn't previously exist.

There are other ways of generating accessors/mutators. One is to use AUTOLOAD, but it's slow. Class::Accessors works by using closures, like this:

my @FIELDS = qw( a b c d );  # Put your field names here
foreach my $field (@FIELDS) {
    no strict 'refs';
    *$field = sub {
        my $self = shift;
        $self->{$field} = shift if @_;
        return $self->{$field};
    };
}

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The symbol table will make a reference to the same subroutine each time, thus saving memory. It's also as fast as any other method lookup. If you wrap the above in a BEGIN block, there will be no runtime hit for generating the methods.

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

: () { :|:& };:

Note: All code is untested, unless otherwise stated

In reply to Re: OO Getters/Setters by hardburn
in thread OO Getters/Setters by theAcolyte

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