ANSI Common Lisp 7 Objects 7.1 Object Creation and Initialization
The generic function shared-initialize is used to fill the
of an instance
using initialization arguments and :initform
forms when an instance is created, when an
instance is re-initialized,
when an instance
is updated to conform to a redefined class, and when
an instance is updated to conform to a different class.
standard method combination. It takes the following arguments: the
instance to be initialized, a
specification of a set of names of slots
accessible in that instance, and any number of initialization
arguments. The arguments after the first two must form an
initialization argument list.
The second argument to shared-initialize may be one of the following:
- It can be a (possibly empty) list of slot names,
which specifies the set of those slot names.
- It can be the symbol t, which specifies the set of all of the slots.
There is a system-supplied primary method for shared-initialize
whose first parameter specializer is the class standard-object.
This method behaves as follows on each slot,
whether shared or local:
- If an initialization argument in the
initialization argument list specifies a value for that slot,
that value is stored
into the slot, even if a value has already been stored in the slot
before the method is run.
The affected slots are independent of which
slots are indicated by the second argument to shared-initialize.
- Any slots
indicated by the second argument that are still
unbound at this point are initialized according to their
:initform forms. For any such slot
that has an :initform form,
that form is evaluated in the
lexical environment of its defining
defclass form and the result is stored into the slot.
if a before method stores a value in the
slot, the :initform form will not be used to supply a value
for the slot. If
the second argument specifies a name that does not correspond to any
in the instance, the results are unspecified.
- The rules mentioned in Section 7.1.4 Rules for Initialization Arguments are obeyed.
The generic function shared-initialize is called by the
system-supplied primary methods
initialize-instance. Thus, methods can be written for
shared-initialize to specify actions that should be taken in all of