Ovid <[EMAIL PROTECTED]> writes:
> Apocalypse 12 has the following to say about roles and trust
> (http://www.perl.com/pub/a/2004/04/16/a12.html?page=10)
>
> It's not clear whether roles should be allowed to grant
> trust. In the absence of evidence to the contrary, I'm
> inclined to say not.
>
> In Perl 5, I recently found myself in the annoying position of having a
> method which could accept scalar, array, or hash references. My
> primary code looked similar to this (simplified for clarity):
>
> sub _attributes {
> my ($self, $attrs) = @_;
> return $$attrs if UNIVERSAL::isa( $attrs, 'SCALAR' );
>
> my @attributes = UNIVERSAL::isa( $attrs, 'HASH' )
> ? %$attrs : @$attrs;
> return unless @attributes;
> # more code here
> }
>
> This was a private method, but $attrs is an argument that is passed in
> by the person using my class. It would be nice if I could just assign
> an "attributes" role to the SCALAR, ARRAY, and HASH classes and say
> that only my class could see the method(s) it provides. Thus, my
> caller would be blissfully unaware that I am doing this:
>
> $attrs->attributes; # even if it's an array reference
How about:
my method SCALAR::attributes($self:) { $$self }
my method HASH::attributes(%self:) { %self.kv }
my method ARRAY::attributes(@self:) { [EMAIL PROTECTED] }
method _attributes($attrs) {
my @attributes = $attrs.attributes
return @attributes[0] if @attributes == 1;
...
}
Assuming it's legal.
--
Piers Cawley <[EMAIL PROTECTED]>
http://www.bofh.org.uk/
