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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.
329 spec-list)
332 ;; Keep it as a non-inlined function, so the internals of object don't get
333 ;; hard-coded in random .elc files.
335 "Return some data structure from which can be extracted the slot offset."
340 "Find the index to pass to `aref' to access SLOT."
344 index))))
347 "Pcase patterns to match EIEIO objects.
348 Elements of FIELDS can be of the form (NAME UPAT) in which case the contents of
349 field NAME is matched against UPAT, or they can be of the form NAME which
350 is a shorthand for (NAME NAME)."
353 ;; FIXME: This generates a horrendous mess of redundant let bindings.
354 ;; `pcase' needs to be improved somehow to introduce let-bindings more
355 ;; sparingly, or the byte-compiler needs to be taught to optimize
356 ;; them away.
357 ;; FIXME: `pcase' does not do a good job here of sharing tests&code among
358 ;; various branches.
369 fields))))
370 \f
371 ;;; Simple generators, and query functions. None of these would do
372 ;; well embedded into an object.
373 ;;
379 "Return a string which is OBJ's name."
383 "Return a printed representation for object OBJ.
384 If EXTRA, include that in the string returned to represent the symbol."
392 ;; In the past, every EIEIO object had a `name' field, so we had the two method
393 ;; below "for free". Since this field is very rarely used, we got rid of it
394 ;; and instead we keep it in a weak hash-tables, for those very rare objects
395 ;; that use it.
403 "Set the string which is OBJ's NAME."
411 "Return the class struct defining OBJ."
412 ;; FIXME: We say we return a "struct" but we return a symbol instead!
416 ;; CLOS name, maybe?
420 "Return a Lisp like symbol name for OBJ's class."
427 "Return parent classes to CLASS. (overload of variable).
429 The CLOS function `class-direct-superclasses' is aliased to this function."
435 "Return child classes to CLASS.
436 The CLOS function `class-direct-subclasses' is aliased to this function."
442 ;; Official CLOS functions.
449 "Return first parent class to CLASS. (overload of variable)."
454 "Return t if OBJ is of class-type CLASS."
461 "Return non-nil if OBJ is an instance of CLASS or CLASS' subclasses."
463 ;; class will be checked one layer down
465 ;; Backwards compatibility
469 "Return non-nil if CHILD class is a subclass of CLASS."
472 ;; `eieio-default-superclass' is never mentioned in eieio--class-parents,
473 ;; so we have to special case it here.
487 "Return list of slots available in instances of CLASS."
488 ;; FIXME: This only gives the instance slots and ignores the
489 ;; class-allocated slots.
495 "Return list of slot names available in OBJ."
502 "Fetch from CLASS, SLOT's :initarg."
510 f))
512 ;;; Object Set macros
513 ;;
515 "Set the value in OBJ for slot SLOT to VALUE.
516 SLOT is the slot name as specified in `defclass' or the tag created
517 with in the :initarg slot. VALUE can be any Lisp object."
522 "Set the default slot in CLASS for SLOT to VALUE.
523 The default value is usually set with the :initform tag during class
524 creation. This allows users to change the default behavior of classes
525 after they are created."
529 ;;; CLOS queries into classes and slots
530 ;;
532 "Return non-nil if OBJECT's SLOT is bound.
533 Setting a slot's value makes it bound. Calling `slot-makeunbound' will
534 make a slot unbound.
535 OBJECT can be an instance or a class."
536 ;; Skip typechecking while retrieving this value.
538 ;; Return nil if the magic symbol is in there.
543 eieio-unbound))))
546 "In OBJECT, make SLOT unbound."
550 "Return non-nil if OBJECT-OR-CLASS has SLOT."
556 ;; FIXME: We could speed this up by adding class slots into the
557 ;; index-table (e.g. with a negative index?).
559 found)
563 found))))
566 "Return the class that SYMBOL represents.
567 If there is no class, nil is returned if ERRORP is nil.
568 If ERRORP is non-nil, `wrong-argument-type' is signaled."
574 ;;; Slightly more complex utility functions for objects
575 ;;
577 "Return an object if KEY is `equal' to SLOT's value of an object in LIST.
578 LIST is a list of objects whose slots are searched.
579 Objects in LIST do not need to have a slot named SLOT, nor does
580 SLOT need to be bound. If these errors occur, those objects will
581 be ignored."
584 ;; This prevents errors for missing slots.
591 "Return an association list with the contents of SLOT as the key element.
592 LIST must be a list of objects with SLOT in it.
593 This is useful when you need to do completing read on an object group."
599 assoclist))
604 "Return an association list with the contents of SLOT as the key element.
605 LIST must be a list of objects, but those objects do not need to have
606 SLOT in it. If it does not, then that element is left out of the association
607 list."
614 assoclist)))
619 "In OBJECT's SLOT, add ITEM to the list of elements.
620 Optional argument APPEND indicates we need to append to the list.
621 If ITEM already exists in the list in SLOT, then it is not added.
622 Comparison is done with `equal' through the `member' function call.
623 If SLOT is unbound, bind it to the list containing ITEM."
625 ;; Find the originating list.
629 ;; turn it into a list.
632 ;; Do the combination
638 ;; Set back into the slot.
642 "In OBJECT's SLOT, remove occurrences of ITEM.
643 Deletion is done with `delete', which deletes by side effect,
644 and comparisons are done with `equal'.
645 If SLOT is unbound, do nothing."
647 nil
650 ;;; Here are some CLOS items that need the CL package
651 ;;
653 ;; FIXME: Shouldn't this be a more complex gv-expander which extracts the
654 ;; common code between oref and oset, so as to reduce the redundant work done
655 ;; in (push foo (oref bar baz)), like we do for the `nth' expander?
658 \f
659 ;;;
660 ;; We want all objects created by EIEIO to have some default set of
661 ;; behaviors so we can create object utilities, and allow various
662 ;; types of error checking. To do this, create the default EIEIO
663 ;; class, and when no parent class is specified, use this as the
664 ;; default. (But don't store it in the other classes as the default,
665 ;; allowing for transparent support.)
666 ;;
669 nil
670 "Default parent class for classes with no specified parent class.
671 Its slots are automatically adopted by classes with no specified parents.
672 This class is not stored in the `parent' slot of a class vector."
680 "Make a new instance of CLASS based on INITARGS.
681 For example:
683 (make-instance 'foo)
685 INITARGS is a property list with keywords based on the `:initarg'
686 for each slot. For example:
694 "Default constructor for CLASS `eieio-default-superclass'.
695 SLOTS are the initialization slots used by `initialize-instance'.
696 This static method is called when an object is constructed.
697 It allocates the vector used to represent an EIEIO object, and then
698 calls `initialize-instance' on that object."
705 "Obsolete name %S passed to %S constructor"
707 ;; Call the initialize method on the new object with the slots
708 ;; that were passed down to us.
710 ;; Return the created object.
711 new-object))
713 ;; FIXME: CLOS uses "&rest INITARGS" instead.
715 "Set slots of OBJ with SLOTS which is a list of name/value pairs.
719 "Set slots of OBJ with SLOTS which is a list of name/value pairs.
720 Called from the constructor routine."
729 ;; FIXME: CLOS uses "&rest INITARGS" instead.
735 "Construct the new object THIS based on SLOTS.
736 SLOTS is a tagged list where odd numbered elements are tags, and
737 even numbered elements are the values to store in the tagged slot.
738 If you overload the `initialize-instance', there you will need to
739 call `shared-initialize' yourself, or you can call `call-next-method'
740 to have this constructor called automatically. If these steps are
741 not taken, then new objects of your class will not have their values
742 dynamically set from SLOTS."
743 ;; First, see if any of our defaults are `lambda', and
744 ;; re-evaluate them and apply the value to our slots.
748 ;; For each slot, see if we need to evaluate it.
749 ;;
750 ;; Paul Landes said in an email:
751 ;; > CL evaluates it if it can, and otherwise, leaves it as
752 ;; > the quoted thing as you already have. This is by the
753 ;; > Sonya E. Keene book and other things I've look at on the
754 ;; > web.
759 ;; FIXME: We should be able to just do (aset this (+ i <cst>) dflt)!
761 ;; Shared initialize will parse our slots for us.
769 "Method invoked when an attempt to access a slot in OBJECT fails.
770 SLOT-NAME is the name of the failed slot, OPERATION is the type of access
771 that was requested, and optional NEW-VALUE is the value that was desired
772 to be set.
774 This method is called from `oref', `oset', and other functions which
775 directly reference slots in EIEIO objects."
777 slot-name)))
783 class slot-name fn)
784 "Slot unbound is invoked during an attempt to reference an unbound slot.
785 OBJECT is the instance of the object being reference. CLASS is the
786 class of OBJECT, and SLOT-NAME is the offending slot. This function
787 throws the signal `unbound-slot'. You can overload this function and
788 return the value to use in place of the unbound value.
789 Argument FN is the function signaling this error.
790 Use `slot-boundp' to determine if a slot is bound or not.
792 In CLOS, the argument list is (CLASS OBJECT SLOT-NAME), but
793 EIEIO can only dispatch on the first argument, so the first two are swapped."
796 slot-name fn)))
799 "Make a copy of OBJ, and then supply PARAMS.
800 PARAMS is a parameter list of the same form used by `initialize-instance'.
802 When overloading `clone', be sure to call `call-next-method'
806 "Make a copy of OBJ, and then apply PARAMS."
812 nobj))
818 "Destructor for cleaning up any dynamic links to our object.
819 Argument THIS is the object being destroyed. PARAMS are additional
820 ignored parameters."
821 ;; No cleanup... yet.
822 )
825 "Pretty printer for object THIS. Call function `object-name' with STRINGS.
827 It is sometimes useful to put a summary of the object into the
828 default #<notation> string when using EIEIO browsing tools.
832 "Pretty printer for object THIS. Call function `object-name' with STRINGS.
833 The default method for printing object THIS is to use the
834 function `object-name'.
836 It is sometimes useful to put a summary of the object into the
837 default #<notation> string when using EIEIO browsing tools.
839 Implement this function and specify STRINGS in a call to
840 `call-next-method' to provide additional summary information.
841 When passing in extra strings from child classes, always remember
842 to prepend a space."
849 "Write out object THIS to the current stream.
853 "Write object THIS out to the current stream.
854 This writes out the vector version of this object. Complex and recursive
855 object are discouraged from being written.
856 If optional COMMENT is non-nil, include comments when outputting
857 this object."
866 ;; Now output readable lisp to recreate this object
867 ;; It should look like this:
868 ;; (<constructor> <name> <slot> <slot> ... )
869 ;; Each slot's slot is writen using its :writer.
876 ;; Loop over all the public slots
891 ;; Use our public printer
896 v))
897 ;; Use our generic override prin1 function.
907 "Perform a `prin1' on THING taking advantage of object knowledge."
917 "Display LIST where list may contain objects."
934 \f
935 ;;; Unimplemented functions from CLOS
936 ;;
938 "Change the class of OBJ to type CLASS.
939 This may create or delete slots, but does not affect the return value
940 of `eq'."
943 ;; Hook ourselves into help system for describing classes and methods.
946 ;;; Interfacing with edebug
947 ;;
949 "Display EIEIO OBJECT in fancy format.
951 Used as advice around `edebug-prin1-to-string', held in the
952 variable PRINT-FUNCTION. Optional argument NOESCAPE is passed to
953 `prin1-to-string' when appropriate."
967 \f
968 ;;; Start of automatically extracted autoloads.
969 \f
970 ;;;### (autoloads nil "eieio-custom" "eieio-custom.el" "916f54b818479a77a02f3ecccda84a11")
971 ;;; Generated autoloads from eieio-custom.el
974 Customize OBJ in a custom buffer.
975 Optional argument GROUP is the sub-group of slots to display.
979 ;;;***
980 \f
981 ;;;### (autoloads nil "eieio-opt" "eieio-opt.el" "899e10c7883c4aac5cefcc223794e8f9")
982 ;;; Generated autoloads from eieio-opt.el
985 Create an object browser window to show all objects.
986 If optional ROOT-CLASS, then start with that, otherwise start with
987 variable `eieio-default-superclass'.
992 Print help description for CLASS.
993 If CLASS is actually an object, then also display current values of that object.
998 Describe CTR if it is a class constructor.
1002 ;;;***
1003 \f
1004 ;;; End of automatically extracted autoloads.
1008 ;;; eieio ends here