Calling arbitrary method from new

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

I feel like this is a very simple question, but I can't seem to find the answer.

I'm trying to create a new class. Most of my accessors are dynamically generated with AUTOLOAD, but I have a few that need to verify data instead of blindly accepting it. Take this code as example:

sub new {
        my $class = shift;
        my %args = @_;
        my %hash = (
                _foo    => 0,
                _bar    => 0,
                _baz    => 0,
        );

        my $self = bless( \%hash, $class );

        ...

        return $self;
}

sub AUTOLOAD {
        # do stuff to auto-generate accessors for anything in my %hash
+ (except without preceding underscore), so "foo" and "bar"
}

sub baz {
        # actually verify input data here
}
[download]

Now, where my "..." is in the new method, I was doing something like this:

        foreach ( keys %args ) {
                if( exists $hash{ '_' . $_ } ) {
                        $self->{ $_ } = $args{ $_ };
                }
        }
[download]

So if I called my new as This::Object->new( bar=>7, baz=>9 );, this would just put each value into my object. But, obviously, I want to actually verify this data, so what I really want to do is call the appropriate accessor method, but I can't seem to figure out how. So, in this example, the 'new' method would do something like call $self->bar( 7 ) and $self->baz( 9 )

Can somebody please point me to the appropriate documentation for this? It almost certainly has to be very common-place in class creation. Thanks in advance for the help!

-Bryan

Comment on Calling arbitrary method from new Select or Download Code

Replies are listed 'Best First'.
Re: Calling arbitrary method from new by chromatic (Archbishop) on Jun 10, 2005 at 03:32 UTC
Are you looking for something like: `for my $argument ( keys %args ) { $self->$argument( $args{ $argument } ) if exists $hash{ '_' . $argument }; }` [download] As a side note, I prefer to generate accessors at compile-time without using `AUTOLOAD` when possible. Unless you predeclare all of the methods you're generating with subs or provide your own `can()`, you've made life more difficult for users of your code.	[reply] [d/l] [select]
Re^2: Calling arbitrary method from new by mrborisguy (Hermit) on Jun 10, 2005 at 03:41 UTC
Yes, I believe that is exactly what I want. I was trying to do something like `$self->&{ $argument }( ... )`, so I can't believe I didn't try this. On the other note: Is it really better to declare all of my methods, even if they are all so similar? I was reading through one of the intro to OO articles in the perldocs, which said AUTOLOAD is good, but I can see your point. Maybe I'll have to rewrite some of my code then. Thanks for the help! -Bryan	[reply] [d/l]
Re^3: Calling arbitrary method from new by tlm (Prior) on Jun 10, 2005 at 03:50 UTC
No ampersand, but the way chromatic wrote it: `$self->$argument( ... )` [download] Recently there was an interesting discussion on the use of `AUTOLOAD` for accessor generation; it starts here. In particular, tilly's first reply illustrates the approach that chromatic alluded to. the lowliest monk	[reply] [d/l]
Re^3: Calling arbitrary method from new by hv (Prior) on Jun 10, 2005 at 08:21 UTC
If I have a number of very similar methods, I like to highlight that by generating them in a loop with something like: `for my $method (qw/ foo bar /) { no strict 'refs'; *$method = sub { use strict 'refs'; my $self = shift; $self->{"_$method"} = shift if @_; return $self->{"_$method"}; } }` [download] I'd usually use AUTOLOAD for this only if the list is infinite - for example if attribute methods are created on demand for arbitrary attributes supplied for the user. Hugo	[reply] [d/l]