The return type of return $this->time; (DateTime) is incompatible with the return type declared by the interface hiqdev\php\billing\ActionInterface::getTime of type hiqdev\php\billing\DateTime.
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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97
}
98
99
/**
100
* {@inheritdoc}
101
*/
102
public function calculateCharge(PriceInterface $price)
The method calculateSum() does not seem to exist on object<hiqdev\php\billing\AbstractAction>.
This check looks for calls to methods that do not seem to exist on a given type.
It looks for the method on the type itself as well as in inherited classes or
implemented interfaces.
This is most likely a typographical error or the method has been renamed.
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114
if ($sum === null) {
115
return null;
116
}
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return new Charge($this, $price->getTarget(), $price->getType(), $usage, $sum);
The return type of return new \hiqdev\php\b...tType(), $usage, $sum); (hiqdev\php\billing\Charge) is incompatible with the return type declared by the interface hiqdev\php\billing\Actio...erface::calculateCharge of type hiqdev\php\billing\ChargeInterface.
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.
Loading history...
119
}
120
121
122
/**
123
* @inheritdoc
124
*/
125
abstract public function isApplicable(PriceInterface $price);
hiqdev /
php-billing
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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_functionexpects aPostobject, and outputs the author of the post. The base classPostreturns a simple string and outputting a simple string will work just fine. However, the child classBlogPostwhich is a sub-type ofPostinstead decided to return anobject, and is therefore violating the SOLID principles. If aBlogPostwere passed tomy_function, PHP would not complain, but ultimately fail when executing thestrtouppercall in its body.