PHP（7.1）继承问题

Question

I have the following structure:

class AffiliateRepository extends GenericRepository implements IAffiliateRepository {

}


abstract class GenericRepository  {
    public function save(BaseModel $model) : int{
        $model->save();
        return $model->getId();
    }

}

interface IAffiliateRepository  {

    public function save(Affiliate $affiliate) : int;
}

public class Affiliate extends BaseModel{}


$affiliateRepository  = new AffiliateRepository();
$affiliateRepository->save(new Affiliate());

I am expecting GenericRepository to take care on the save action.

but I'm getting the following error:

Declaration of App\Services\AffiliateRepository::save(App\Models\Affiliate $affiliate): int should be compatible with App\Services\GenericRepository::save(App\Models\BaseModel $model): int

Why is that? Affiliate inherits from BaseModel.
Whats the best way to overcome that and let GenericRepository handle the save function call.

thanks

Answer 1

Look at methods:

// GenericRepository
public function save(BaseModel $model)

// IAffiliateRepository
public function save(Affiliate $affiliate) : int;

Both classes have to expect the same type. If you implement IAffiliateRepository into GenericRepository class, it will be correct. You may also need to change variable names to be the same.