Why? The common new can support it:

sub new {
    my $class = shift;
    bless @_ ? shift : \ my $x, $class;
}
[download]

That way you can use an arbitrary foreign object as the donator of the new id.

Anno

Sorry - I fail to see how this helps in subclassing an pre-existing class. What you seem to be doing here is taking an existing object and re-blessing it into your new class - which will break inheritance, method resolution, etc.

It will work as long as the @ISA gets set up correctly. It's no different than what Class::InsideOut does to support inside-out objects. All anno's solution does is provide a default constructor that can take a foreign object.

That said, I'm not sure where it really helps as his solution still either requires an overridding new to add an initialization call or else will provide an explicit call to an init or BUILD. The former approach doesn't really save any code and the latter approach is another straightjacket -- however comfy. Put differently, his new just makes it easier to generate either an anonymous scalar or to rebless an existing object.

-xdg

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