Re^2: Perl's equivalent to Python's hasattr and getattr? (class variable details)


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Re^2: Perl's equivalent to Python's hasattr and getattr? (class variable details)

by MistaMuShu (Beadle)

on Jul 28, 2005 at 23:46 UTC ( [id://479178]=note: print w/replies, xml )

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in reply to Re: Perl's equivalent to Python's hasattr and getattr? (class variable details)
in thread Perl's equivalent to Python's hasattr and getattr? (class variable details)

Wow, that hits it right on the spot! I find it weird that this isn't builtin. Maybe I'll skim through and look up how Class::Accessor is implemented. Is it possible to do something similar theorically by manipulating symbol tables?

Comment on Re^2: Perl's equivalent to Python's hasattr and getattr? (class variable details)

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Re^3: Perl's equivalent to Python's hasattr and getattr? (class variable details)
by rlb3 (Deacon) on Jul 29, 2005 at 00:03 UTC

Class::Accessor is built using the symbol table. Here is the _mk_accessors as an example.

{
    no strict 'refs';

    sub _mk_accessors {
        my($self, $maker, @fields) = @_;
        my $class = ref $self || $self;

        # So we don't have to do lots of lookups inside the loop.
        $maker = $self->can($maker) unless ref $maker;

        foreach my $field (@fields) {
            if( $field eq 'DESTROY' ) {
                require Carp;
                &Carp::carp("Having a data accessor named DESTROY  in 
+".
                             "'$class' is unwise.");
            }

            my $accessor = $self->$maker($field);
            my $alias = "_${field}_accessor";

            *{$class."\:\:$field"}  = $accessor
              unless defined &{$class."\:\:$field"};

            *{$class."\:\:$alias"}  = $accessor
              unless defined &{$class."\:\:$alias"};
        }
    }
}
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