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php – Collisions with other trait methods

Posted by: admin April 23, 2020 Leave a comment

Questions:

How can I deal with traits with methods of same name?

trait FooTrait {
  public function fooMethod() {
        return 'foo method';
  }

  public function getRow() {
        return 'foo row';
  }
}

trait TooTrait {
    public function tooMethod() {
        return 'too method';
    }

    public function getRow() {
        return 'too row';
    }
}

class Boo
{
    use FooTrait;
    use TooTrait;

    public function booMethod() {
        return $this->fooMethod();
    }
}

error,

Fatal error: Trait method getRow has not been applied, because there
are collisions with other trait methods on Boo in…

What should I do about it?

And also, with two same method names, how can I get the method from trait FooTrait?

$a = new Boo;
var_dump($a->getRow()); // Fatal error: Call to undefined method Boo::getRow() in... 

Edit:

class Boo
{
    use FooTrait, TooTrait {
        FooTrait::getRow insteadof TooTrait;
    }

    public function booMethod() {
        return $this->fooMethod();
    }
}

what if I want to get the method getRow from TooTrait via Boo as well? Is it possible?

How to&Answers:

PHP Documentation about conflicts:

If two Traits insert a method with the same name, a fatal error is
produced, if the conflict is not explicitly resolved.

To resolve naming conflicts between Traits used in the same class, the
insteadof operator needs to be used to chose exactly one of the
conflicting methods.

Since this only allows one to exclude methods, the as operator can be
used to allow the inclusion of one of the conflicting methods under
another name.

Example #5 Conflict Resolution

In this example, Talker uses the traits A and B. Since A and B have
conflicting methods, it defines to use the variant of smallTalk from
trait B, and the variant of bigTalk from trait A.

The Aliased_Talker makes use of the as operator to be able to use B’s
bigTalk implementation under an additional alias talk.

<?php
trait A {
    public function smallTalk() {
        echo 'a';
    }

    public function bigTalk() {
        echo 'A';
    }
}

trait B {
    public function smallTalk() {
        echo 'b';
    }

    public function bigTalk() {
        echo 'B';
    }
}

class Talker {
    use A, B {
        B::smallTalk insteadof A;
        A::bigTalk insteadof B;
    }
}

class Aliased_Talker {
    use A, B {
        B::smallTalk insteadof A;
        A::bigTalk insteadof B;
        B::bigTalk as talk;
    }
}

So in your case it could be

class Boo {
    use FooTrait, TooTrait {
        FooTrait::getRow insteadof TooTrait;
    }

    public function booMethod() {
        return $this->fooMethod();
    }
}

(it works even if you do separate use, but i think it’s more clear)

Or use the as to declare an alias.

Answer:

yes this is possible you can use something like this (answer for edited content) :

class Boo {
    use FooTrait, TooTrait {
        FooTrait::getRow as getFooRow;
        TooTrait::getRow as getTooRow;
    }

    public function getRow(... $arguments)
    {
         return [ 'foo' => $this->getFooRow(... $arguments), 'too' => $this->getTooRow(... $arguments) ];
    }

    public function booMethod(... $arguments)
    {
        return $this->getFooRow(... $arguments);
    }
}