As merlyn showed me before, you could alternatively use 'can' to check
whether $me is an object or not, and leave it alone when it is, trusting
that the class of the object is fine:
if ( ref $me and $me->can('can') ){
.....
I did have some discussion with tye about can, and at the time he
convinced me to use isa instead: ... $me->isa('UNIVERSAL').
More importantly, reading perlbot I realised that all that caution
about bless is unnecessary. So I rephrase my advise above:
There is nothing special about constructors other than that
they bless a variable. Since you are allowed to rebless a variable, just
call the constructors at will.
In perlbot you can find more info and an example of nested constructors.
Reblessing assumes that the caller knows what (s)he is doing and
that the constructor should always return an object of its own class. This
antagonizes the logic behind bless-checking. The reblessing approach is
the most flexible one, as constructors do not have to make assumptions
about which class the returned objects should be in.
This in turn made me realise that multiple inheritance could, with a little
caution, even apply to the object's data. Just call both constructors and
merge the resulting anonymous arrays. Problems will arise when the
inherited classes use the same hash-entries for different purposes or when
different types of variables are used, of
course. At the end, one just reblesses the anonymous hash.
Jeroen "We are not alone"(FZ) |