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1 ;;; eieio.el --- Enhanced Implementation of Emacs Interpreted Objects -*- lexical-binding:t -*-
2 ;;; or maybe Eric's Implementation of Emacs Interpreted Objects
4 ;; Copyright (C) 1995-1996, 1998-2015 Free Software Foundation, Inc.
6 ;; Author: Eric M. Ludlam <zappo@gnu.org>
7 ;; Version: 1.4
8 ;; Keywords: OO, lisp
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software: you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation, either version 3 of the License, or
15 ;; (at your option) any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;;; Commentary:
26 ;;
27 ;; EIEIO is a series of Lisp routines which implements a subset of
28 ;; CLOS, the Common Lisp Object System. In addition, EIEIO also adds
29 ;; a few new features which help it integrate more strongly with the
30 ;; Emacs running environment.
31 ;;
32 ;; See eieio.texi for complete documentation on using this package.
33 ;;
34 ;; Note: the implementation of the c3 algorithm is based on:
35 ;; Kim Barrett et al.: A Monotonic Superclass Linearization for Dylan
36 ;; Retrieved from:
37 ;; http://192.220.96.201/dylan/linearization-oopsla96.html
39 ;; @TODO - fix :initform to be a form, not a quoted value
40 ;; @TODO - Prefix non-clos functions with `eieio-'.
42 ;; TODO: better integrate CL's defstructs and classes. E.g. make it possible
43 ;; to create a new class that inherits from a struct.
45 ;;; Code:
51 "Display the current version of EIEIO."
57 \f
58 ;;; Defining a new class
59 ;;
61 "Define NAME as a new class derived from SUPERCLASS with SLOTS.
62 OPTIONS-AND-DOC is used as the class' options and base documentation.
63 SUPERCLASSES is a list of superclasses to inherit from, with SLOTS
64 being the slots residing in that class definition. Supported tags are:
66 :initform - Initializing form.
67 :initarg - Tag used during initialization.
68 :accessor - Tag used to create a function to access this slot.
69 :allocation - Specify where the value is stored.
70 Defaults to `:instance', but could also be `:class'.
71 :writer - A function symbol which will `write' an object's slot.
72 :reader - A function symbol which will `read' an object.
73 :type - The type of data allowed in this slot (see `typep').
74 :documentation
75 - A string documenting use of this slot.
77 The following are extensions on CLOS:
78 :custom - When customizing an object, the custom :type. Public only.
79 :label - A text string label used for a slot when customizing.
80 :group - Name of a customization group this slot belongs in.
81 :printer - A function to call to print the value of a slot.
82 See `eieio-override-prin1' as an example.
84 A class can also have optional options. These options happen in place
85 of documentation (including a :documentation tag), in addition to
86 documentation, or not at all. Supported options are:
88 :documentation - The doc-string used for this class.
90 Options added to EIEIO:
92 :allow-nil-initform - Non-nil to skip typechecking of null initforms.
93 :custom-groups - List of custom group names. Organizes slots into
94 reasonable groups for customizations.
95 :abstract - Non-nil to prevent instances of this class.
96 If a string, use as an error string if someone does
97 try to make an instance.
98 :method-invocation-order
99 - Control the method invocation order if there is
100 multiple inheritance. Valid values are:
101 :breadth-first - The default.
102 :depth-first
104 Options in CLOS not supported in EIEIO:
106 :metaclass - Class to use in place of `standard-class'
107 :default-initargs - Initargs to use when initializing new objects of
108 this class.
110 Due to the way class options are set up, you can add any tags you wish,
111 and reference them using the function `class-option'."
126 ;; Make sure the method invocation order is a valid value.
136 ;; Collect the accessors we need to define.
149 :initform
150 :initarg
151 :documentation
152 :protection
153 :reader
154 :writer
155 :allocation
156 :type
157 :custom
158 :label
159 :group
160 :printer
161 :allow-nil-initform
166 ;; Make sure the :allocation parameter has a valid value.
170 ;; Label is nil, or a string
174 ;; Is there an initarg, but allocation of class?
178 ;; Anyone can have an accessor function. This creates a function
179 ;; of the specified name, and also performs a `defsetf' if applicable
180 ;; so that users can `setf' the space returned by this function.
184 accessors)
187 "Retrieve the slot `%S' from an object of class `%S'."
188 sname name)
189 ;; FIXME: Why is this different from the :reader case?
191 accessors)
193 ;; FIXME: How could I declare this *method* as obsolete.
196 "Retrieve the class slot `%S' from a class `%S'.
197 This method is obsolete."
198 sname name)
201 accessors)))
203 ;; If a writer is defined, then create a generic method of that
204 ;; name whose purpose is to set the value of the slot.
208 sname name)
210 accessors))
211 ;; If a reader is defined, then create a generic method
212 ;; of that name whose purpose is to access this slot value.
216 sname name)
218 accessors))
219 ))
222 ;; This test must be created right away so we can have self-
223 ;; referencing classes. ei, a class whose slot can contain only
224 ;; pointers to itself.
226 ;; Create the test functions.
236 ;; When using typep, (typep OBJ 'myclass) returns t for objects which
237 ;; are subclasses of myclass. For our predicates, however, it is
238 ;; important for EIEIO to be backwards compatible, where
239 ;; myobject-p, and myobject-child-p are different.
240 ;; "cl" uses this technique to specify symbols with specific typep
241 ;; test, so we can let typep have the CLOS documented behavior
242 ;; while keeping our above predicate clean.
248 ,@accessors
250 ;; Create the constructor function
252 ;; Abstract classes cannot be instantiated. Say so.
260 ;; Non-abstract classes need a constructor.
263 name)
267 whole
271 ;; Keep the name arg, for backward compatibility,
272 ;; but hide it so we don't trigger indefinitely.
278 ;;; Get/Set slots in an object.
279 ;;
281 "Retrieve the value stored in OBJ in the slot named by SLOT.
282 Slot is the name of the slot when created by `defclass' or the label
283 created by the :initarg tag."
292 "Get the default value of OBJ (maybe a class) for SLOT.
293 The default value is the value installed in a class with the :initform
294 tag. SLOT can be the slot name, or the tag specified by the :initarg
295 tag in the `defclass' call."
299 ;;; Handy CLOS macros
300 ;;
302 "Bind SPEC-LIST lexically to slot values in OBJECT, and execute BODY.
303 This establishes a lexical environment for referring to the slots in
304 the instance named by the given slot-names as though they were
305 variables. Within such a context the value of the slot can be
306 specified by using its slot name, as if it were a lexically bound
307 variable. Both setf and setq can be used to set the value of the
308 slot.
310 SPEC-LIST is of a form similar to `let'. For example:
312 ((VAR1 SLOT1)
313 SLOT2
314 SLOTN
315 (VARN+1 SLOTN+1))
317 Where each VAR is the local variable given to the associated
318 SLOT. A slot specified without a variable name is given a
319 variable name of the same name as the slot."
322 ;; Transform the spec-list into a cl-symbol-macrolet spec-list.
327 spec-list)))
329 body)))
330 \f
331 ;;; Simple generators, and query functions. None of these would do
332 ;; well embedded into an object.
333 ;;
338 "Return a string which is OBJ's name."
342 "Return a printed representation for object OBJ.
343 If EXTRA, include that in the string returned to represent the symbol."
351 ;; In the past, every EIEIO object had a `name' field, so we had the two method
352 ;; below "for free". Since this field is very rarely used, we got rid of it
353 ;; and instead we keep it in a weak hash-tables, for those very rare objects
354 ;; that use it.
362 "Set the string which is OBJ's NAME."
370 "Return the class struct defining OBJ."
371 ;; FIXME: We say we return a "struct" but we return a symbol instead!
375 ;; CLOS name, maybe?
379 "Return a Lisp like symbol name for OBJ's class."
386 "Return parent classes to CLASS. (overload of variable).
388 The CLOS function `class-direct-superclasses' is aliased to this function."
394 "Return child classes to CLASS.
395 The CLOS function `class-direct-subclasses' is aliased to this function."
401 ;; Official CLOS functions.
408 "Return first parent class to CLASS. (overload of variable)."
413 "Return t if OBJ is of class-type CLASS."
420 "Return non-nil if OBJ is an instance of CLASS or CLASS' subclasses."
422 ;; class will be checked one layer down
424 ;; Backwards compatibility
428 "Return non-nil if CHILD class is a subclass of CLASS."
431 ;; `eieio-default-superclass' is never mentioned in eieio--class-parent,
432 ;; so we have to special case it here.
445 "Return list of slots available in instances of CLASS."
446 ;; FIXME: This only gives the instance slots and ignores the
447 ;; class-allocated slots.
448 ;; FIXME: It only gives the slot's *names* rather than actual
449 ;; slot descriptors.
455 "Return list of slots available in OBJ."
468 f))
470 ;;; Object Set macros
471 ;;
473 "Set the value in OBJ for slot SLOT to VALUE.
474 SLOT is the slot name as specified in `defclass' or the tag created
475 with in the :initarg slot. VALUE can be any Lisp object."
480 "Set the default slot in CLASS for SLOT to VALUE.
481 The default value is usually set with the :initform tag during class
482 creation. This allows users to change the default behavior of classes
483 after they are created."
487 ;;; CLOS queries into classes and slots
488 ;;
490 "Return non-nil if OBJECT's SLOT is bound.
491 Setting a slot's value makes it bound. Calling `slot-makeunbound' will
492 make a slot unbound.
493 OBJECT can be an instance or a class."
494 ;; Skip typechecking while retrieving this value.
496 ;; Return nil if the magic symbol is in there.
501 eieio-unbound))))
504 "In OBJECT, make SLOT unbound."
508 "Return non-nil if OBJECT-OR-CLASS has SLOT."
515 ))
518 "Return the class that SYMBOL represents.
519 If there is no class, nil is returned if ERRORP is nil.
520 If ERRORP is non-nil, `wrong-argument-type' is signaled."
526 ;;; Slightly more complex utility functions for objects
527 ;;
529 "Return an object if KEY is `equal' to SLOT's value of an object in LIST.
530 LIST is a list of objects whose slots are searched.
531 Objects in LIST do not need to have a slot named SLOT, nor does
532 SLOT need to be bound. If these errors occur, those objects will
533 be ignored."
536 ;; This prevents errors for missing slots.
543 "Return an association list with the contents of SLOT as the key element.
544 LIST must be a list of objects with SLOT in it.
545 This is useful when you need to do completing read on an object group."
551 assoclist))
556 "Return an association list with the contents of SLOT as the key element.
557 LIST must be a list of objects, but those objects do not need to have
558 SLOT in it. If it does not, then that element is left out of the association
559 list."
566 assoclist)))
571 "In OBJECT's SLOT, add ITEM to the list of elements.
572 Optional argument APPEND indicates we need to append to the list.
573 If ITEM already exists in the list in SLOT, then it is not added.
574 Comparison is done with `equal' through the `member' function call.
575 If SLOT is unbound, bind it to the list containing ITEM."
577 ;; Find the originating list.
581 ;; turn it into a list.
584 ;; Do the combination
590 ;; Set back into the slot.
594 "In OBJECT's SLOT, remove occurrences of ITEM.
595 Deletion is done with `delete', which deletes by side effect,
596 and comparisons are done with `equal'.
597 If SLOT is unbound, do nothing."
599 nil
602 ;;; Here are some CLOS items that need the CL package
603 ;;
605 ;; FIXME: Shouldn't this be a more complex gv-expander which extracts the
606 ;; common code between oref and oset, so as to reduce the redundant work done
607 ;; in (push foo (oref bar baz)), like we do for the `nth' expander?
610 \f
611 ;;;
612 ;; We want all objects created by EIEIO to have some default set of
613 ;; behaviors so we can create object utilities, and allow various
614 ;; types of error checking. To do this, create the default EIEIO
615 ;; class, and when no parent class is specified, use this as the
616 ;; default. (But don't store it in the other classes as the default,
617 ;; allowing for transparent support.)
618 ;;
621 nil
622 "Default parent class for classes with no specified parent class.
623 Its slots are automatically adopted by classes with no specified parents.
624 This class is not stored in the `parent' slot of a class vector."
632 "Make a new instance of CLASS based on INITARGS.
633 For example:
635 (make-instance 'foo)
637 INITARGS is a property list with keywords based on the `:initarg'
638 for each slot. For example:
646 "Default constructor for CLASS `eieio-default-superclass'.
647 SLOTS are the initialization slots used by `initialize-instance'.
648 This static method is called when an object is constructed.
649 It allocates the vector used to represent an EIEIO object, and then
650 calls `initialize-instance' on that object."
657 "Obsolete name %S passed to %S constructor"
659 ;; Call the initialize method on the new object with the slots
660 ;; that were passed down to us.
662 ;; Return the created object.
663 new-object))
665 ;; FIXME: CLOS uses "&rest INITARGS" instead.
667 "Set slots of OBJ with SLOTS which is a list of name/value pairs.
671 "Set slots of OBJ with SLOTS which is a list of name/value pairs.
672 Called from the constructor routine."
681 ;; FIXME: CLOS uses "&rest INITARGS" instead.
687 "Construct the new object THIS based on SLOTS.
688 SLOTS is a tagged list where odd numbered elements are tags, and
689 even numbered elements are the values to store in the tagged slot.
690 If you overload the `initialize-instance', there you will need to
691 call `shared-initialize' yourself, or you can call `call-next-method'
692 to have this constructor called automatically. If these steps are
693 not taken, then new objects of your class will not have their values
694 dynamically set from SLOTS."
695 ;; First, see if any of our defaults are `lambda', and
696 ;; re-evaluate them and apply the value to our slots.
700 ;; For each slot, see if we need to evaluate it.
701 ;;
702 ;; Paul Landes said in an email:
703 ;; > CL evaluates it if it can, and otherwise, leaves it as
704 ;; > the quoted thing as you already have. This is by the
705 ;; > Sonya E. Keene book and other things I've look at on the
706 ;; > web.
710 ;; Next.
712 ;; Shared initialize will parse our slots for us.
720 "Method invoked when an attempt to access a slot in OBJECT fails.
721 SLOT-NAME is the name of the failed slot, OPERATION is the type of access
722 that was requested, and optional NEW-VALUE is the value that was desired
723 to be set.
725 This method is called from `oref', `oset', and other functions which
726 directly reference slots in EIEIO objects."
728 slot-name)))
734 class slot-name fn)
735 "Slot unbound is invoked during an attempt to reference an unbound slot.
736 OBJECT is the instance of the object being reference. CLASS is the
737 class of OBJECT, and SLOT-NAME is the offending slot. This function
738 throws the signal `unbound-slot'. You can overload this function and
739 return the value to use in place of the unbound value.
740 Argument FN is the function signaling this error.
741 Use `slot-boundp' to determine if a slot is bound or not.
743 In CLOS, the argument list is (CLASS OBJECT SLOT-NAME), but
744 EIEIO can only dispatch on the first argument, so the first two are swapped."
747 slot-name fn)))
750 "Make a copy of OBJ, and then supply PARAMS.
751 PARAMS is a parameter list of the same form used by `initialize-instance'.
753 When overloading `clone', be sure to call `call-next-method'
757 "Make a copy of OBJ, and then apply PARAMS."
763 nobj))
769 "Destructor for cleaning up any dynamic links to our object.
770 Argument THIS is the object being destroyed. PARAMS are additional
771 ignored parameters."
772 ;; No cleanup... yet.
773 )
776 "Pretty printer for object THIS. Call function `object-name' with STRINGS.
778 It is sometimes useful to put a summary of the object into the
779 default #<notation> string when using EIEIO browsing tools.
783 "Pretty printer for object THIS. Call function `object-name' with STRINGS.
784 The default method for printing object THIS is to use the
785 function `object-name'.
787 It is sometimes useful to put a summary of the object into the
788 default #<notation> string when using EIEIO browsing tools.
790 Implement this function and specify STRINGS in a call to
791 `call-next-method' to provide additional summary information.
792 When passing in extra strings from child classes, always remember
793 to prepend a space."
800 "Write out object THIS to the current stream.
804 "Write object THIS out to the current stream.
805 This writes out the vector version of this object. Complex and recursive
806 object are discouraged from being written.
807 If optional COMMENT is non-nil, include comments when outputting
808 this object."
817 ;; Now output readable lisp to recreate this object
818 ;; It should look like this:
819 ;; (<constructor> <name> <slot> <slot> ... )
820 ;; Each slot's slot is writen using its :writer.
827 ;; Loop over all the public slots
836 )
843 ;; Use our public printer
847 ;; Use our generic override prin1 function.
859 "Perform a `prin1' on THING taking advantage of object knowledge."
869 "Display LIST where list may contain objects."
886 \f
887 ;;; Unimplemented functions from CLOS
888 ;;
890 "Change the class of OBJ to type CLASS.
891 This may create or delete slots, but does not affect the return value
892 of `eq'."
895 ;; Hook ourselves into help system for describing classes and methods.
898 ;;; Interfacing with edebug
899 ;;
901 "Display EIEIO OBJECT in fancy format.
903 Used as advice around `edebug-prin1-to-string', held in the
904 variable PRINT-FUNCTION. Optional argument NOESCAPE is passed to
905 `prin1-to-string' when appropriate."
919 \f
920 ;;; Start of automatically extracted autoloads.
921 \f
922 ;;;### (autoloads nil "eieio-custom" "eieio-custom.el" "2ec91e473fcad1ff20cd76edc4aab706")
923 ;;; Generated autoloads from eieio-custom.el
926 Customize OBJ in a custom buffer.
927 Optional argument GROUP is the sub-group of slots to display.
931 ;;;***
932 \f
933 ;;;### (autoloads nil "eieio-opt" "eieio-opt.el" "d1910eb455f102989fc33bb3f5a9b614")
934 ;;; Generated autoloads from eieio-opt.el
937 Create an object browser window to show all objects.
938 If optional ROOT-CLASS, then start with that, otherwise start with
939 variable `eieio-default-superclass'.
944 Print help description for CLASS.
945 If CLASS is actually an object, then also display current values of that object.
950 Describe CTR if it is a class constructor.
954 ;;;***
955 \f
956 ;;; End of automatically extracted autoloads.
960 ;;; eieio ends here