Once any behavior is added, the simple use of can to test for attributes is no longer robust.

You're right and I thought about this a bit. If every package and ISA package has a %HAS (or HASA) hash containing valid attributes as keys, and defines a 'has' method, then its fairly simple to validate attributes in any package (and the attribute accessor/mutator methods could even be AUTOLOAD'ed if desired). The 'has' method would go something like this (untested):

sub has {
  my ($self, $attr) = @_;
  return 1 if exists $HAS{$attr};
  return 1 if ${_}::has($self, $attr) for @ISA;
  return;
}

# Then in initialization or in AUTOLOAD...
...
if ($self->has($attr)) {
 ...#set attr
}

[download]
I'm not yet saying that this is a good idea, just throwing it out there for comments/opinions/better options.

In reply to Re: Beware can for attrs by runrig
in thread (my?) problem with re-blessed references(?) by BrowserUk

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