defclass-std - Standard class writing macro

Most times, when sketching out a new class, I often commit lots of typos and forget to add an :initform.

Also, the throw away class designed in the beginning may thrive and stay the same. If only there was a way to overcome these problems... There is!

This simple macro atempts to give a very DRY and succint interface to the common DEFCLASS form. The goal is to offer most of the capabilities of a normal DEFCLASS, only in a more compact way.

Everything compiles down to DEFCLASS.

Usage

* (ql:quickload :defclass-std)
; => (:DEFCLASS-STD)
* (import 'defclass-std:defclass/std)
; => T

A simple class defined with DEFCLASS/STD looks like this:

(defclass/std example ()
  ((slot1 slot2 slot3)))

; which expands to:

(DEFCLASS EXAMPLE ()
  ((SLOT1 :ACCESSOR SLOT1 :INITARG :SLOT1 :INITFORM NIL)
   (SLOT2 :ACCESSOR SLOT2 :INITARG :SLOT2 :INITFORM NIL)
   (SLOT3 :ACCESSOR SLOT3 :INITARG :SLOT3 :INITFORM NIL)))

As you can see, by default, the macro adds three options:

1. :accessor + the name of the slot
2. :initarg + the name of the slot
3. :initform nil

If you want to change the :initform value, you can use the :std option:

(defclass std-test ()
  ((slot :std 1)))

; expands to:

(DEFCLASS STD-TEST ()
  ((SLOT :ACCESSOR SLOT :INITARG :SLOT :INITFORM 1)))

If you want to omit the :initform option, you have two ways:

1. Use :std :unbound explicitly
2. Change the value of *default-std*. By default it is set to T, so, when the :std option is omitted, :initform is set to nil. When *default-std* is set to nil, :initform is omitted when :std is omitted.

(defclass/std omit-std ()
  ((slot :std :unbound)))

; which is (semantically) equivalent to:
(eval-when (:compile-toplevel :load-toplevel :execute)
  (setf *default-std* nil))
(defclass/std omit-std ()
  ((slot)))

; which (both) expands to:

(DEFCLASS OMIT-STD ()
  ((SLOT :ACCESSOR SLOT :INITARG :SLOT)))

:a, :i, :r and :w are connected: when all of them are omitted, :a and :i are inserted by default.

:a stands for :accessor, :i stands for :initarg, :r stands for :reader and :w stands for :writer.

If any of those is present, the default (:a and :i) is omitted.

(defclass/std airw ()
  ((slot1 slot2)
   (slot3 slot4 :r)
   (slot5 :w)
   (slot6 :a)
   (slot7 :ri)))

; which expands to:

(DEFCLASS AIRW ()
  ((SLOT1 :ACCESSOR SLOT1 :INITARG :SLOT1 :INITFORM NIL)
   (SLOT2 :ACCESSOR SLOT2 :INITARG :SLOT2 :INITFORM NIL)
   (SLOT3 :READER SLOT3 :INITFORM NIL)
   (SLOT4 :READER SLOT4 :INITFORM NIL)
   (SLOT5 :WRITER SLOT5 :INITFORM NIL)
   (SLOT6 :ACCESSOR SLOT6 :INITFORM NIL)
   (SLOT7 :READER SLOT7 :INITARG :SLOT7 :INITFORM NIL)))

Note that slot7 has an :ri option. That's just :r and :i together.

If you want to use :r and :w together, use :a instead, or you'll get an error. The same stands for :a + :r and :a + :w.

You can choose to add the class name as a prefix for the acessor/reader/writer function. Just put :with or :with-prefix option.

(defclass/std example ()
  ((slot1 :with)
   (slot2)))

; which expands to:

(DEFCLASS EXAMPLE ()
  ((SLOT1 :ACCESSOR EXAMPLE-SLOT1 :INITARG :SLOT1 :INITFORM NIL)
   (SLOT2 :ACCESSOR SLOT2 :INITARG :SLOT2 :INITFORM NIL)))

To make a slot static (class-allocated), use :@@ or :static.

To declare the type of a slot or to add documentation to a slot, use :type and :doc, respectively.

For real quick, concise, dense and standard class definitions, use CLASS/STD:

(class/std example slot1 slot2 slot3)

; which expands to:

(DEFCLASS/STD EXAMPLE ()
  ((SLOT1 SLOT2 SLOT3)))

; which expands to:

(DEFCLASS EXAMPLE ()
  ((SLOT1 :ACCESSOR SLOT1 :INITARG :SLOT1 :INITFORM NIL)
   (SLOT2 :ACCESSOR SLOT2 :INITARG :SLOT2 :INITFORM NIL)
   (SLOT3 :ACCESSOR SLOT3 :INITARG :SLOT3 :INITFORM NIL)))

You can also add the prefix by default by changing the value of the *with-prefix* special variable (defaults to nil):

(eval-when (:compile-toplevel :load-toplevel :execute)
  (setf *with-prefix* t))
(defclass/std pre ()
  ((fix)))

; which expands to:

(DEFCLASS PRE ()
  ((FIX :ACCESSOR PRE-FIX :INITARG :FIX)))

Unknown keywords are left intact:

(defclass/std unknown ()
  ((slot :unknown :keywords)))

; which expands to:

(DEFCLASS UNKNOWN ()
  ((SLOT :ACCESSOR SLOT :INITARG :SLOT :INITFORM NIL :KEYWORDS :UNKNOWN)))


; Or, even using custom accessors:

(defclass/std unknown ()
  ((slot :unknown :wi :keywords)))

; which expands to:

(DEFCLASS UNKNOWN ()
  ((SLOT :WRITER SLOT :INITARG :SLOT :INITFORM NIL :KEYWORDS :UNKNOWN)))

Examples

(defclass/std computer (gadget)
  ((screen mouse keyboard :a :type string :with-prefix)
   (bluetooth touchpad :wi)
   (speaker microphone :r)
   (place :@@ :with :doc "Where it is" :r)
   (owner :static :std "Me" :w)))

  ; expands to:

(DEFCLASS COMPUTER (GADGET)
  ((SCREEN :ACCESSOR COMPUTER-SCREEN :INITFORM NIL :TYPE STRING)
   (MOUSE :ACCESSOR COMPUTER-MOUSE :INITFORM NIL :TYPE STRING)
   (KEYBOARD :ACCESSOR COMPUTER-KEYBOARD :INITFORM NIL :TYPE STRING)
   (BLUETOOTH :WRITER BLUETOOTH :INITARG :BLUETOOTH :INITFORM NIL)
   (TOUCHPAD :WRITER TOUCHPAD :INITARG :TOUCHPAD :INITFORM NIL)
   (SPEAKER :READER SPEAKER :INITFORM NIL)
   (MICROPHONE :READER MICROPHONE :INITFORM NIL)
   (PLACE :READER COMPUTER-PLACE :INITFORM NIL :ALLOCATION :CLASS
          :DOCUMENTATION "Where it is")
   (OWNER :WRITER OWNER :INITFORM "Me" :ALLOCATION :CLASS)))

Real life examples:

From cl-inflector:

(defclass language ()
  ((name :accessor name :initarg :name :initform nil)
   (plurals :accessor plurals :initarg :plurals :initform nil)
   (singulars :accessor singulars :initarg :singulars :initform nil)
   (uncountables :accessor uncountables :initarg :uncountables :initform nil)
   (irregulars :accessor irregulars :initarg :irregulars :initform nil)))

; could be written:

(defclass/std language ()
  ((name plurals singulars uncountables irregulars)))

; or, using CLASS/STD:

(class/std language name plurals singulars uncountables irregulars)

From clack:

(defclass <handler> ()
     ((server-name :type keyword
                   :initarg :server-name
                   :accessor server-name)
      (acceptor :initarg :acceptor
                :accessor acceptor)))

; could be written (with *default-std* set to nil)
(defclass/std language ()
  ((server-name :type keyword)
   (acceptor)))

From RESTAS:

(defclass route (routes:route)
  ((symbol :initarg :symbol :reader route-symbol)
   (module :initarg :module :initform nil :reader route-module)
   (required-method :initarg :required-method :initform nil
                    :reader route-required-method)
   (arbitrary-requirement :initarg :arbitrary-requirement :initform nil
                          :reader route-arbitrary-requirement)
   (render-method :initarg :render-method :initform #'identity)
   (headers :initarg :headers :initform nil :reader route-headers)
   (variables :initarg :variables :initform nil)
   (additional-variables :initarg :additional-variables :initform nil)))

; could be written
(defclass/std route (routes-route)
  ((symbol :ri :with-prefix :std :unbound)
   (module required-method arbitrary-requirement
           headers variables additional-variables :ri)
   (render-method :i :std #'identity)
   (header :ir)))

From defclass-star example:

(defclass configuration ()
  ((package-name      :type symbol  :initarg :package-name      :accessor package-name-of)
   (package-nicknames :initform '() :initarg :package-nicknames :accessor package-nicknames-of)
   (included-files    :initform '() :initarg :included-files    :accessor included-files-of)
   (gccxml-path       :initform "gccxml" :initarg :gccxml-path  :accessor gccxml-path-of)
   (gccxml-flags      :initform ""  :initarg :gccxml-flags      :accessor gccxml-flags-of)
   (hidden-symbols    :initform '() :initarg :hidden-symbols    :accessor hidden-symbols-of)
   (output-filename   :initform nil :initarg :output-filename   :accessor output-filename-of)
   (options           :initform (standard-configuration-options)
                      :initarg :options
                      :accessor options-of)
   (symbol-export-filter :initform 'standard-symbol-export-filter
                         :type (or (function (symbol)) symbol)
                         :initarg :symbol-export-filter
                         :accessor symbol-export-filter-of)
   (function-name-transformer :initform 'standard-name-transformer
                              :type (or (function (string)) symbol)
                              :initarg :function-name-transformer
                              :accessor function-name-transformer-of)
   (variable-name-transformer :initform 'standard-name-transformer
                              :type (or (function (string)) symbol)
                              :initarg :variable-name-transformer
                              :accessor variable-name-transformer-of)
   (type-name-transformer :initform 'standard-name-transformer
                          :type (or (function (string)) symbol)
                          :initarg :type-name-transformer
                          :accessor type-name-transformer-of)
   (temp-directory    :initform (make-pathname :directory "/tmp")
                      :initarg :temp-directory
                      :accessor temp-directory-of)
   (working-directory :initform *default-pathname-defaults*
                      :initarg :working-directory
                      :accessor working-directory-of)))

;;; And the equivalent defclass* version (56 tree leaves):
(defclass* configuration ()
  ((package-name
                              :type symbol)
   (package-nicknames         '())
   (included-files            '())
   (gccxml-path               "gccxml")
   (gccxml-flags              "")
   (hidden-symbols            '())
   (output-filename           nil)
   (options                   (standard-configuration-options))
   (symbol-export-filter      'standard-symbol-export-filter
                              :type (or (function (symbol)) symbol))
   (function-name-transformer 'standard-name-transformer
                              :type (or (function (string)) symbol))
   (variable-name-transformer 'standard-name-transformer
                              :type (or (function (string)) symbol))
   (type-name-transformer     'standard-name-transformer
                              :type (or (function (string)) symbol))
   (temp-directory            (make-pathname :directory "/tmp"))
   (working-directory         *default-pathname-defaults*)))

;; And the equivalent defclass/std version (46 tree leaves):
(defclass/std configuration ()
  ((package-name :type symbol :std :unbound)
   (package-nicknames included-files hidden-symbols output-filename)
   (gccxml-path :std "gccxml")
   (gccxml-flags :std "")
   (options :std (standard-configuration-options))
   (symbol-export-filter :std 'standard-symbol-export-filter
                         :type (or (function (symbol)) symbol))
   (function-name-transformer variable-name-transformer type-name-transformer
                              :std 'standard-name-transformer
                              :type (or (function (string)) symbol))
   (temp-directory :std (make-pathname :directory "/tmp"))
   (working-directory :std *default-pathname-defaults*)))

From cl-hue:

(defclass light ()
  ((bridge :initarg :bridge :accessor light-bridge)
   (number :initarg :number :accessor light-number)
   (type :initarg :type :accessor light-type)
   (name :initarg :name :accessor light-name)
   (modelid :initarg :modelid :accessor light-modelid)
   (uniqueid :initarg :uniqueid :accessor light-uniqueid)
   (swversion :initarg :swversion :accessor light-swversion)
   (pointsymbol :initarg :pointsymbol :accessor light-pointsymbol)
   (on :initarg :on :accessor light-on-p)
   (brightness :initarg :brightness :accessor light-brightness)
   (hue :initarg :hue :accessor light-hue)
   (saturation :initarg :saturation :accessor light-saturation)
   (xy :initarg :xy :accessor light-xy)
   (ct :initarg :ct :accessor light-ct)
   (alert :initarg :alert :accessor light-alert)
   (effect :initarg :effect :accessor light-effect)
   (colormode :initarg :colormode :accessor light-colormode)
   (reachable :initarg :reachable :accessor light-reachable-p)))

; could be written:
(defclass/std light ()
  ((bridge number type name modelid uniqueid swversion pointsymbol on brightness
           hue saturation xy ct alert effect colormode reachable
           :with-prefix :std :unbound)))

; or, using class/std:

(class/std light
  bridge number type name modelid uniqueid swversion pointsymbol on brightness
  hue saturation xy ct alert effect colormode reachable
  :std :unbound :with)

; or, with *default-std* set to nil and *with-prefix* set to t:

(class/std light
  bridge number type name modelid uniqueid swversion pointsymbol on brightness
  hue saturation xy ct alert effect colormode reachable)

There's a shortcut to setup a basic printing behaviour of a class, using printing-unreadably:

(printing-unreadably (field2 field3) (class/std myclass field1 field2 field3))

; which expands to:

(PROGN
  (CLASS/STD MYCLASS FIELD1 FIELD2 FIELD3)
  (DEFMETHOD PRINT-OBJECT ((MYCLASS MYCLASS) #:STREAM1722)
    (PRINT-UNREADABLE-OBJECT (MYCLASS #:STREAM1722 :TYPE T :IDENTITY T)
      (FORMAT #:STREAM1722 "FIELD2: ~s, FIELD3: ~s"
              (FIELD2 MYCLASS) (FIELD3 MYCLASS)))))

Dependencies

This project depends only on Anaphora and Alexandria libraries. The test package uses the prove test library.

Installation

Available on Quicklisp:

(ql:quickload :defclass-std)

Bugs

If you find any bug or inconsistency in the code, or if you find it too hard to use, please, feel free to open an issue.

Tests

This library is tested under ABCL, SBCL, CCL, CLISP and ECL Common Lisp implementations.

To run all the defined tests, use:

* (asdf:test-system :defclass-std)
; prints lots of (colorful) stuff...
; => T

Tests are ran with Travis CI and Circle CI using cl-travis, CIM, cl-coveralls and Roswell. Check it out!

Authors

• André Miranda
• Joram Schrijver

License

LLGPL.