Re: [Sbcl-devel] possible bug?

[Christophe R. <cs...@ca...>]

Alexey Dejneka <ade...@co...> writes:

>> (defmethod make-instance :around ((instance (eql 'CONTEXT)) &rest rest 
>> &key name &allow-other-keys)
>
> AMOP, section "Restrictions on Portable Programs":
>
> AMOP> Any method defined by a portable program on a specified generic
> AMOP> function must have at least one specializer that is neither a
> AMOP> specified class nor an eql specializer whose associated value is
> AMOP> an instance of a specified class.
>
> So, it seems that you need to create your own metaclass, make CONTEXT
> be an instance of it and specialize MAKE-INSTANCE on (FIND-CLASS
> 'CONTEXT).

In addition to this, the specified behaviour of MAKE-INSTANCE is to
"create and return a new instance of the given class" (accoring to
ANSI); "The result is a newly allocated and initialized instance of
class" (says AMOP): defining methods which violate this contract, even
if not explicitly forbidden anywhere, is generally a bad idea.
Defining an ENSURE-CONTEXT function is probably the way forward.

Cheers,

Christophe