Re: [cdi-dev] Challenge TCK test for indirect specialization rules
----- Original Message -----
From: "Jozef Hartinger" <jharting(a)redhat.com>
To: "Matus Abaffy" <maabaffy(a)redhat.com>, "Mark Struberg"
<struberg(a)yahoo.de>
Cc: cdi-dev(a)lists.jboss.org
Sent: Friday, June 6, 2014 10:17:31 AM
Subject: Re: [cdi-dev] Challenge TCK test for indirect specialization rules
On 06/03/2014 11:48 AM, Matus Abaffy wrote:
> If the intention was not to ignore the beans in-between, then the rule for
> indirect specialization seems quite redundant to me.
The way indirect specialization is defined in the spec is equivalent to
saying that "specialization" relation is transitive. Having
A specializes B
and
B specializes C
that means that also
"A specializes C"
holds true.
I agree that when looking at qualifiers and name only, this "A
specializes C" relation may seem redundant. Relations "A specializes B"
and "B specializes C" themselves guarantee
that B contains all the qualifiers of C, A contains all the qualifiers
of B (and thus also those from C).
However, there are other parts of the specification for which the fact
that both "A specializes B" and "A specializes C" hold true is
important.
Yes, of course, I am aware of these. I kind of misexpressed myself.
What I wanted to say is that the indirect specialization is redundantly
contained in "Then X will inherit the qualifiers and bean name of Y:".
I think the following suffices:
'If X directly specializes Y, then X will inherit the qualifiers and bean name of
Y:'
For example, take section 5.1.2.
It says:
"A bean is said to be enabled if it is not specialized by any other
enabled bean".
Now it makes a difference whether we consider specialization transitive
(A specializes C relation exists) or not as it influences whether C ends
up being enabled or not.
Transitive case:
Both B and C are specialized by A and thus only A remains enabled.
Non-transitive case:
A is enabled. B is specialized by A this B is not enabled. C is only
specialized by B, which is *not enabled* thus C remains enabled. Now
having both A and C enabled at the same time is clearly wrong and goes
against the whole purpose of specialization. Instead of replacing C with
A we end up we both beans enabled.
I think there is no doubt now that non-transitive specialization does
not fit the CDI spec. In addition, I hope this makes it clear why
transitivity of specialization is not redundant.
Jozef