Re: Union `&` operator

Yes. And I think it will be good if enforced by language. On Sat, Nov 7, 2020, 5:33 PM Olle Härstedt <olleharstedt@gmail.com> wrote: > 2020-11-07 15:12 GMT, Eugene Sidelnyk <zsidelnik@gmail.com>: > > When you follow ISP, you probably would have a lot of interfaces. > > Thus, client code may require an object to implement a bunch of > interfaces > > depending on functionality needed. > > > > Consider class Bar: > > > > ```php > > > > interface A {} > > > > interface B {} > > > > interface C {} > > > > interface D {} > > > > interface E {} > > > > class Bar implements A, B, C, D, E { > > // > > } > > ``` > > > > > > And some code, which uses Bar, but depends rather on > > interfaces, which > > functionality is actually needed: > > > > ```php > > function foo(A & B & E $object) { > > // some work > > > > var_dump($object); > > } > > ``` > > > > It is currently feasable like this (ugly): > > > > ```php > > function foo(A $object) { > > (function(B $object) { > > > > (function(E $object) { > > > > // some work > > > > var_dump($object); > > > > })($object); > > > > })($object); > > } > > ``` > > > > Or like this (more readable, but still): > > > > ```php > > function foo(A | B | E $object) { > > > > if (!$object instanceof A) { > > throw new \RuntimeException(); > > } > > > > if (!$object instanceof B) { > > throw new \RuntimeException(); > > } > > > > if (!$object instanceof E) { > > throw new \RuntimeException(); > > } > > > > // some work > > > > var_dump($object); > > } > > ``` > > > > Another possible option is to create interface, which combines > > A, B, > > E, but in some cases it would lead us to interfaces > > explosion. > > > > This idea proposes to eliminate instanceof checks by > > introducing & > > union operator. > > > > You mean intersections? Psalm supports this notation. >