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19 CLOS compatibility

Currently, the following functions should behave almost as expected from CLOS.

defclass
All slot keywords are available but not all work correctly. Slot keyword differences are:
:reader, and :writer tags
Create methods that signal errors instead of creating an unqualified method. You can still create new ones to do its business.
:accessor
This should create an unqualified method to access a slot, but instead pre-builds a method that gets the slot's value.
:type
Specifier uses the typep function from the cl package. See Type Predicates. It therefore has the same issues as that package. Extensions include the ability to provide object names.

Defclass also supports class options, but does not currently use values of :metaclass, and :default-initargs.

make-instance
Make instance works as expected, however it just uses the EIEIO instance creator automatically generated when a new class is created. See Making New Objects.
defgeneric
Creates the desired symbol, and accepts all of the expected arguments except :around.
defmethod
Calls defgeneric, and accepts most of the expected arguments. Only the first argument to the created method may have a type specifier. To type cast against a class, the class must exist before defmethod is called. In addition, the :around tag is not supported.
call-next-method
Inside a method, calls the next available method up the inheritance tree for the given object. This is different than that found in CLOS because in EIEIO this function accepts replacement arguments. This permits subclasses to modify arguments as they are passed up the tree. If no arguments are given, the expected CLOS behavior is used.
setf
If the common-lisp subsystem is loaded, the setf parameters are also loaded so the form (setf (slot-value object slot) t) should work.

CLOS supports the describe command, but EIEIO only provides eieio-describe-class, and eieio-describe-generic. These functions are adviced into describe-variable, and describe-function.

When creating a new class (see Building Classes) there are several new keywords supported by EIEIO.

In EIEIO tags are in lower case, not mixed case.