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diff --git a/locale/fr/LC_MESSAGES/_tils/2021-04-24-common-lisp-argument-precedence-order-parameterization-of-a-generic-function.po b/locale/fr/LC_MESSAGES/_tils/2021-04-24-common-lisp-argument-precedence-order-parameterization-of-a-generic-function.po new file mode 100644 index 0000000..6aa66a8 --- /dev/null +++ b/locale/fr/LC_MESSAGES/_tils/2021-04-24-common-lisp-argument-precedence-order-parameterization-of-a-generic-function.po @@ -0,0 +1,210 @@ +# +msgid "" +msgstr "" + +msgid "" +"title: Common Lisp argument precedence order parameterization of a generic " +"function" +msgstr "" + +msgid "layout: post" +msgstr "" + +msgid "lang: en" +msgstr "" + +msgid "" +"ref: common-lisp-argument-precedence-order-parameterization-of-a-generic-" +"function" +msgstr "" + +msgid "" +"When CLOS dispatches a method, it picks the most specific method definition " +"to the argument list:" +msgstr "" + +msgid "" +"\n" +"* (defgeneric a-fn (x))\n" +"#<STANDARD-GENERIC-FUNCTION A-FN (0) {5815ACB9}>\n" +"\n" +"* (defmethod a-fn (x) :default-method)\n" +"#<STANDARD-METHOD A-FN (T) {581DB535}>\n" +"\n" +"* (defmethod a-fn ((x number)) :a-number)\n" +"#<STANDARD-METHOD A-FN (NUMBER) {58241645}>\n" +"\n" +"* (defmethod a-fn ((x (eql 1))) :number-1)\n" +"#<STANDARD-METHOD A-FN ((EQL 1)) {582A7D75}>\n" +"\n" +"* (a-fn nil)\n" +":DEFAULT-METHOD\n" +"\n" +"* (a-fn \"1\")\n" +":DEFAULT-METHOD\n" +"\n" +"* (a-fn 0)\n" +":A-NUMBER\n" +"\n" +"* (a-fn 1)\n" +":NUMBER-1\n" +msgstr "" + +msgid "" +"CLOS uses a similar logic when choosing the method from parent classes, when" +" multiple ones are available:" +msgstr "" + +msgid "" +"* (defclass class-a () ())\n" +"\n" +"#<STANDARD-CLASS CLASS-A {583E0B25}>\n" +"* (defclass class-b () ())\n" +"\n" +"#<STANDARD-CLASS CLASS-B {583E7F6D}>\n" +"* (defgeneric another-fn (obj))\n" +"\n" +"#<STANDARD-GENERIC-FUNCTION ANOTHER-FN (0) {583DA749}>\n" +"* (defmethod another-fn ((obj class-a)) :class-a)\n" +"; Compiling LAMBDA (.PV-CELL. .NEXT-METHOD-CALL. OBJ):\n" +"; Compiling Top-Level Form:\n" +"\n" +"#<STANDARD-METHOD ANOTHER-FN (CLASS-A) {584523C5}>\n" +"* (defmethod another-fn ((obj class-b)) :class-b)\n" +"; Compiling LAMBDA (.PV-CELL. .NEXT-METHOD-CALL. OBJ):\n" +"; Compiling Top-Level Form:\n" +"\n" +"#<STANDARD-METHOD ANOTHER-FN (CLASS-B) {584B8895}>\n" +msgstr "" + +msgid "" +"Given the above definitions, when inheriting from `class-a` and `class-b`, " +"the order of inheritance matters:" +msgstr "" + +msgid "" +"* (defclass class-a-coming-first (class-a class-b) ())\n" +"#<STANDARD-CLASS CLASS-A-COMING-FIRST {584BE6AD}>\n" +"\n" +"* (defclass class-b-coming-first (class-b class-a) ())\n" +"#<STANDARD-CLASS CLASS-B-COMING-FIRST {584C744D}>\n" +"\n" +"* (another-fn (make-instance 'class-a-coming-first))\n" +":CLASS-A\n" +"\n" +"* (another-fn (make-instance 'class-b-coming-first))\n" +":CLASS-B\n" +msgstr "" + +msgid "" +"Combining the order of inheritance with generic functions with multiple " +"arguments, CLOS has to make a choice of how to pick a method given two " +"competing definitions, and its default strategy is prioritizing from left to" +" right:" +msgstr "" + +msgid "" +"* (defgeneric yet-another-fn (obj1 obj2))\n" +"#<STANDARD-GENERIC-FUNCTION YET-ANOTHER-FN (0) {584D9EC9}>\n" +"\n" +"* (defmethod yet-another-fn ((obj1 class-a) obj2) :first-arg-specialized)\n" +"#<STANDARD-METHOD YET-ANOTHER-FN (CLASS-A T) {5854269D}>\n" +"\n" +"* (defmethod yet-another-fn (obj1 (obj2 class-b)) :second-arg-specialized)\n" +"#<STANDARD-METHOD YET-ANOTHER-FN (T CLASS-B) {585AAAAD}>\n" +"\n" +"* (yet-another-fn (make-instance 'class-a) (make-instance 'class-b))\n" +":FIRST-ARG-SPECIALIZED\n" +msgstr "" + +msgid "" +"For that, we use the `:argument-precedence-order` option when declaring a " +"generic function:" +msgstr "" + +msgid "" +"* (defgeneric yet-another-fn (obj1 obj2) (:argument-precedence-order obj2 obj1))\n" +"#<STANDARD-GENERIC-FUNCTION YET-ANOTHER-FN (2) {584D9EC9}>\n" +"\n" +"* (yet-another-fn (make-instance 'class-a) (make-instance 'class-b))\n" +":SECOND-ARG-SPECIALIZED\n" +msgstr "" + +msgid "" +"I liked that the `:argument-precedence-order` option exists. We shouldn't " +"have to change the arguments from `(obj1 obj2)` to `(obj2 obj1)` just to " +"make CLOS pick the method that we want. We can configure its default " +"behaviour if desired, and keep the order of arguments however it best fits " +"the generic function." +msgstr "" + +msgid "Comparison with Clojure" +msgstr "" + +msgid "Clojure has an equivalent, when using `defmulti`." +msgstr "" + +msgid "" +"Since when declaring a multi-method with `defmulti` we must define the " +"dispatch function, Clojure uses it to pick the method definition. Since the " +"dispatch function is required, there is no need for a default behaviour, " +"such as left-to-right." +msgstr "" + +msgid "Conclusion" +msgstr "" + +msgid "" +"Making the argument precedence order configurable for generic functions but " +"not for class definitions makes a lot of sense." +msgstr "" + +msgid "" +"One shouldn't change the order of arguments of a generic function for the " +"sake of tailoring it to the CLOS priority ranking algorithm, but doing it " +"for a class definition is just fine." +msgstr "" + +msgid "TIL." +msgstr "" + +msgid "" +"CLOS has to make a choice between the first and the second definition of " +"`yet-another-fn`, but its choice is just a heuristic. What if we want the " +"choice to be based on the second argument, instead of the first?" +msgstr "" + +msgid "" +"When declaring a class, we can choose the precedence order, and that is " +"about it. But when defining a generic function, the order of arguments is " +"more important to the function semantics, and the argument precedence being " +"left-to-right is just the default behaviour." +msgstr "" + +msgid "References" +msgstr "" + +msgid "" +"[Object-Oriented Programming in Common Lisp: A Programmer's Guide to " +"CLOS](https://en.wikipedia.org/wiki/Object-" +"Oriented_Programming_in_Common_Lisp), by Sonja E. Keene" +msgstr "" + +msgid "date: 2021-04-24 2" +msgstr "" + +#~ msgid "date: 2021-04-24" +#~ msgstr "" + +#~ msgid "" +#~ "CLOS has to make a choice between the first and the second definition of " +#~ "`yet-another-fn`, but its choice is just a heuristic. What if we want to the" +#~ " choice to be based on the second argument first?" +#~ msgstr "" + +#~ msgid "" +#~ "When declaring a class, we can choose the precedence order, and that is " +#~ "about it. But when defining a generic function, the order of argumentws is " +#~ "more important to the function semantics, and the argument precedence being " +#~ "left-to-right is just the default behaviour." +#~ msgstr "" |