#286 :ALLOCATION kind not extensible
[This actually a MOP compliance issue.]
One of the use cases of the CLOS Metaobject Protocol is to be able to add
one's own :allocation kinds. The book "The Art of the Metaobject Protocol"
describes the addition of hash-table-based slots as an example, and the
CLOS MOP specification has wording that suggests that the kinds
of :allocation is not restricted to the set supported by CLOS by default
(i.e., :instance and :clos). See the specification of ALLOCATE-INSTANCE in
the CLOS MOP specification that talks about slots with allocation :instance
on the one hand and slots "with any other allocation" on the other hand.
I have attached a test case in which a hash-table-based slot access is
implemented. The relevant part is that the method compute-effective-
slot-definition accepts the :allocation :hash in this example. (Since
subclasses of hash-class could add further allocation kinds, this class
doesn't do any further checks here.)
When run.lisp is loaded, which executes the test case, CLisp (erroneously)
complains that the :allocation kinds for the slots defined in the example is
:hash, and not :instance or :class. This code works in current versions of
CMUCL, OpenMCL and SBCL.
Cheers,
Pascal
The test case.
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thank you for your bug report.
the bug has been fixed in the CVS tree.
you can either wait for the next release (recommended)
or check out the current CVS tree (see http://clisp.cons.org\)
and build CLISP from the sources (be advised that between
releases the CVS tree is very unstable and may not even build
on your platform).