Hey Robert,
> On 12 Feb 2015, at 16:15, Robert Stoll <p...@tutteli.ch> wrote:
>
> There are several programming languages which do support dynamic typing and
> method overloading somehow (Clojure, Erlang, Prolog, Cecil and certainly
> more). Most of them use a multi-method approach and I think if PHP would
> introduce function/method overloading, then such an approach would be
> appropriate.
Interesting, I should maybe look into those. I’m not sure if all of those are
really… “dynamic” as such. Are you sure the overloading you’re referring to
there isn’t pattern-matching?
> Right now, I need to implement the dynamic dispatching quasi myself which
> might be more verbose but is also more cumbersome (and uglier IMO). Consider
> the following (fictional example):
>
> I want to write a Logger-Service which provides one public method "log" which
> writes all kind of objects to a log. The corresponding classes do not all
> belong to my code base, are part of third party libraries respectively, so I
> am not able to introduce some interface which all classes implement. The
> strategy pattern is certainly a good idea for this problem but nevertheless,
> somewhere I need to have the distinction based on many if/else with
> instanceof (latest in the LoggerStrategyFactory) -- off topic, if someone has
> a better design approach to handle this problem, then let me know it in a
> private message, would be interesting as well ;)
>
> class Logger{
> public function log($x){
> if($x instanceof Foo){
> logFoo($x);
> }else if($x instanceof Bar){
> logBar($x);
> }
> //...
> }else{
> throw new Exception("type ".gettype($x)." not supported");
> }
> }
> private function logFoo(Foo $f){
> //..
> }
> private function logBar(Bar $b){
> //..
> }
> //...
> }
>
> With method overloading I could write the following, removing the hassle to
> write the dynamic dispatch myself:
>
> class Logger{
> public log(){
> $this->_log($x);
> }
> private function _log(Foo $f){
> //..
> }
> private function _log(Bar $b){
> //..
> }
> //...
> private function _log($x){
> throw new Exception("type ".gettype($x)." not supported");
> }
> }
>
> Which is cleaner IMO.
We could also add some sort of pattern-matching syntax which could do the same
thing, but would have usefulness beyond merely dispatching to multiple methods.
--
Andrea Faulds
http://ajf.me/
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