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Now that we know how to create classes, access slots, and define methods, it might be useful to verify that everything is doing ok. To help with this a plethora of predicates have been created.
Return a vector with all the class’s important parts in it. This vector
is not a copy. Changing this vector changes the class. The CLOS method
find-class
will have the same effect.
CLOS function. In EIEIO it returns the vector definition of the class.
If there is no class, nil
is returned if errorp is
nil
.
Return non-nil
if class is a class type.
Return non-nil
if obj is an object.
Return Non-nil
if obj-or-class contains slot in its class.
Non-nil
if OBJECT’s SLOT is bound.
Setting a slot’s value makes it bound. Calling slot-makeunbound will
make a slot unbound.
OBJECT can be an instance or a class.
Return a string of the form #<class myclassname> which should look similar to other lisp objects like buffers and processes. Printing a class results only in a symbol.
Return the value in CLASS of a given OPTION. For example:
(class-option eieio-default-superclass :documentation) |
Will fetch the documentation string for eieio-default-superclass
.
Return a symbol used as a constructor for class. This way you can make an object of a passed in class without knowing what it is. This is not a part of CLOS.
Return a string of the form #<object-class myobjname> for obj.
This should look like lisp symbols from other parts of emacs such as
buffers and processes, and is shorter and cleaner than printing the
object’s vector. It is more useful to use object-print
to get
and object’s print form, as this allows the object to add extra display
information into the symbol.
Returns the class symbol from obj.
CLOS symbol which does the same thing as object-class
Same as object-class
except this is a macro, and no
type-checking is performed.
Returns the symbol of obj’s class.
Returns the direct parents class of class. Returns nil
if
it is a superclass.
Just like class-parent
except it is a macro and no type checking
is performed.
Deprecated function which returns the first parent of class.
Return the list of classes inheriting from class.
Just like class-children
, but with no checks.
Returns t
if obj’s class is the same as class.
Same as same-class-p
except this is a macro and no type checking
is performed.
Returns t
if obj inherits anything from class. This
is different from same-class-p
because it checks for inheritance.
Returns t
if child is a subclass of class.
Returns t
if method-symbol
is a generic function, as
opposed to a regular emacs list function.
It is also important to note, that for every created class, a two
predicates are created for it. Thus in our example, the function
data-object-p
is created, and return t
if passed an object
of the appropriate type. Also, the function data-object-child-p
is created which returns t
if the object passed to it is of a
type which inherits from data-object
.
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This document was generated by Aidan Kehoe on December 27, 2016 using texi2html 1.82.