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Postings from November 2003
Alan Burlison <Alan.Burlison@sun.com> writes:
>Nicholas Clark wrote:
>
>> IIRC (confirmed by looking at hv.c)
>>
>> SvREADONLY on the hv makes the hash a restricted hash
>> (can't add new keys, can't access keys not present, can delete keys)
>
> From looking at my test script, in 5.6.1 it looks like readonlyness on a
>hash only prevented you from deleting, not from adding new keys.
>
>> SvREADONLY on a key also prevents it from being deleted.
>>
>> (as well as the regular effects of readonlyness)
>
>Umm, what exactly do you mean by 'regular'? Surely deletion is the only
>thing you can do to a hash key anyway?
He meant values not keys
$foo{Fred} .= "Junk";
is 'regular' effect of marking values readonly.
>Do you mean it also makes the
>associated value readonly, or would that have to be set seperately?
>
>> I think that the implementation should have been marked "subject to change"
>> as it's not that clean.
>
>As well as the fact that it breaks existing code :-( FYI, the module in
>question is Sun::Solaris::Kstat, used by the Solaris-specific /bin/kstat
>command. It's more than a little inconvenient that this is broken between
>5.6.1 and 5.8.2, as I have to ship both perl versions in Solaris 10.
>
>When 'restricted hashes' were added did anyone check that XSUB code which
>uses them still behaves sensibly on older versions of perl? You always
>could SvREADONLY_on/off on hashes in 5.6.1, it's unfortunate that the
>restricted hashes stuff has broken older code.
>
>--
>Alan Burlison
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