demerphq++; I mostly agree with what you've said. But Perl already disallows some similar things so I'd really like to make blessing into things like '', '0', 'HASH', and "\0" illegal just to put some things to rest.

I'm quite tired of hearing about how simple code doesn't work in all cases and the resulting discussions of things-that-should-never-be-done that would break the simple code and then people replacing really simple code with really complicated code in order to deal with this nonsense.

Now, this will only fix one of the problems with ref($h) eq 'HASH', but there are other improvements that fix the other problems [UNIVERSAL::isa() and Scalar::Utils].

I'd really like to make blessing into things like '', '0', 'HASH', and "\0" illegal just to put some things to rest.

I'll agree with you with regard to everything but 'HASH' and other type specific designations. Since ref was so ill-conceived from the beginning there will always be code out there that gets nailed by bad coding decisions. Being able to bless a reference so that it appears to crude analysis to be of a different type than than it really is can be a useful workaround. It can be used to deal with bad coding such as ref $obj eq 'HASH' when you want to pass in a blessed hash, or a couple of other tricks like things with overriden deref operators.

Truth be told however, I would almost argue that blessed and reftype should be added to the perl core (without requiring Scalar::Utils) and ref deprecated. I would also make reftype take an optional second argument turning it into a type specific ISA.

I agree that its a real pitty that ref is so poorly thought out. But theres not much to be done about it now.



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demerphq



First they ignore you, then they laugh at you, then they fight you, then you win.
-- Gandhi

Yes, I'd love to see ref deprecated, replacing it with build-in versions of reftype() and blessed() [and I have no reservations about this -- I really think that is exactly what should be done, the sooner the better]. And that should probably be the first step before making it illegal to bless into 'HASH' -- though it feels wrong to use the flaw to justify not fixing the flaw (:

                - tye

I don't think I forgot anything.

I was genuinely asking whether Abigail thought that this was something that I should be testing for in my programs or just another of those many perl quirks that it's good to be aware of but probably pointless actually coding tests for.

Abigail tends to have a very dry sense of humour and I couldn't tell if this was a serious concern for everyday use or not from his post, so I asked.

We could put checks in our code to make sure that someone hasn't re-defined our defined constants, but that would render them pretty pointless.

So, my question remains -- should I be checking the return from ref for definedness every time I call it, or is the possibility of a reference blessed into package 0 (zero) or package '' sufficiently rare and unlikely that I can reasonably ignore the possibility?

I don't think I forgot anything.

Well, it seemed to me that you forgot that its somewhat traditional in Perl to leave as much rope as people need to hang themselves. Personally I dont see it as too much of a problem. *shrugs*

is the possibility of a reference blessed into package 0 (zero) or package '' sufficiently rare and unlikely that I can reasonably ignore the possibility?

In general I would say that you can ignore the possibility. If you happen to decide to write something is supposed to walk any data structrue correctly then I would say that you should consider the whole slew of possibilities in this area.

BTW, I didnt mean to imply that you should be worried about redefining constants. Just that its a useful feature in some respects and the side effect of when it is needed for useful things is that it allows some very dangerous things. As does blessing.

Anyway, cheers.



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demerphq



First they ignore you, then they laugh at you, then they fight you, then you win.
-- Gandhi

I understand the philosophy of perl in this respect, and in many cases I am in favour of it, but only when the rope has a useful purpose beside hanging me:)

I don't yet have enough long-term experience of Perl or the internals to know if there is a useful (if obscure) purpose in allowing blessing into these weird package spaces, and thought to utilise Abigails greater experience to short-circuit that learning curve.

I cannot think of one and felt, as I implied in the original post, that there was "nothing to worry about", but I've been bitten by that feeling before only to be shown the errors of my limited vision (usually by Abigail!).

It's my opinion that if this particular piece of rope has no useful purpose, then I can see no particular reason for leaving it lying around. It doesn't seem (from my cursory inspections of the source) that it wouldn't be a difficult task to coil this particular loose end. I'd even be prepared to have a go at doing it, once I was convinced that there was no such useful purpose. I think tyes earlier reply to you indicates that he feels the same, but that is an interpretation.

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Examine what is said, not who speaks.

"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.