The return type of return $this->canceledAt; (DateTimeInterfac) is incompatible with the return type declared by the interface PH\Component\Core\Model\...nterface::getCanceledAt of type DateTimeInterface|null.
If you return a value from a function or method, it should be a sub-type of the
type that is given by the parent type f.e. an interface, or abstract method.
This is more formally defined by the
Lizkov substitution principle,
and guarantees that classes that depend on the parent type can use any instance
of a child type interchangably. This principle also belongs to the
SOLID principles
for object oriented design.
Our function my_function expects a Post object, and outputs the author
of the post. The base class Post returns a simple string and outputting a
simple string will work just fine. However, the child class BlogPost which
is a sub-type of Post instead decided to return an object, and is
therefore violating the SOLID principles. If a BlogPost were passed to
my_function, PHP would not complain, but ultimately fail when executing the
strtoupper call in its body.
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}
34
35
/**
36
* {@inheritdoc}
37
*/
38
public function setCanceledAt(?\DateTimeInterface $dateTime): void
It seems like $dateTime can also be of type object<DateTimeInterface>. However, the property $canceledAt is declared as type object<DateTimeInterfac>. Maybe add an additional type check?
Our type inference engine has found a suspicous assignment of a value to a property.
This check raises an issue when a value that can be of a mixed type is assigned to
a property that is type hinted more strictly.
For example, imagine you have a variable $accountId that can either hold an
Id object or false (if there is no account id yet). Your code now assigns that
value to the id property of an instance of the Account class. This class
holds a proper account, so the id value must no longer be false.
Either this assignment is in error or a type check should be added for that assignment.
classId{public$id;publicfunction__construct($id){$this->id=$id;}}classAccount{/** @var Id $id */public$id;}$account_id=false;if(starsAreRight()){$account_id=newId(42);}$account=newAccount();if($accountinstanceofId){$account->id=$account_id;}
It seems like $subscription can also be of type object<PH\Component\Subs...\SubscriptionInterface>. However, the property $subscription is declared as type object<PH\Component\Core...\SubscriptionInterface>. Maybe add an additional type check?
Our type inference engine has found a suspicous assignment of a value to a property.
This check raises an issue when a value that can be of a mixed type is assigned to
a property that is type hinted more strictly.
For example, imagine you have a variable $accountId that can either hold an
Id object or false (if there is no account id yet). Your code now assigns that
value to the id property of an instance of the Account class. This class
holds a proper account, so the id value must no longer be false.
Either this assignment is in error or a type check should be added for that assignment.
classId{public$id;publicfunction__construct($id){$this->id=$id;}}classAccount{/** @var Id $id */public$id;}$account_id=false;if(starsAreRight()){$account_id=newId(42);}$account=newAccount();if($accountinstanceofId){$account->id=$account_id;}
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_function
expects aPost
object, and outputs the author of the post. The base classPost
returns a simple string and outputting a simple string will work just fine. However, the child classBlogPost
which is a sub-type ofPost
instead decided to return anobject
, and is therefore violating the SOLID principles. If aBlogPost
were passed tomy_function
, PHP would not complain, but ultimately fail when executing thestrtoupper
call in its body.