How to use Logicexception from PHP?

Question

I’m studying the handling of errors in PHP, and already know how to use Exception, but I was in doubt about the LogicException, what is its purpose? And how to use it correctly?

Answer 1

LogicException according to the PHP documentation, it is kind of exception related to some logic error in your application, which will imply a change in your code.

In other words, it would be the mistakes where "Huuum... this shouldn’t have happened".

Example

I couldn’t think of a more elaborate real situation, but in this case the implementation is working

<?php

Class Divisao
{
    private $divisor;
    private $dividendo;

    public function __construct($dividendo, $divisor){
        $this->dividendo = (int) $dividendo;
        $this->divisor = (int) $divisor;        
    }

    private function valida(){
        // @todo Verifica se o Divisor é Igual a 0
        return true;
    }

    public function dividir(){
        if ($this->valida()){

            // Se mesmo depois da validação o divisor for Zero, temos um erro de lógica.
            if ($this->divisor === 0) throw new LogicException('Validação Falhou');

            return $this->dividendo / $this->divisor;
        }
    }
}
try {
    $d1 = new Divisao(2,2);
    $d2 = new Divisao(2,0);

    echo $d1->dividir();
    echo $d2->dividir();

} catch (LogicException $e) {
    echo "Erro de Lógica " . $e->getMessage();
}

Answer 2

The exception LogicException is released when the code shows some logic error.

Exception representing error in program logic. This type of exception must lead directly to a correction in your code.

The use of LogicException is similar to DomainException, it should be used if your code produces a value that should not produce.

The exception DomainException is launched when a value does not adhere to a defined valid data domain.

Example:

function diaUtil($dia){
    switch ($dia){
        case 2:  echo "Segunda-feira"; break;
        case 3:  echo "Terça-feira";   break;
        case 4:  echo "Quarta-feira";  break;
        case 5:  echo "Quinta-feira";  break;
        case 6:  echo "Sexta-Feira";   break;
        default:
                 throw new DomainException("Não é um dia útil válido");
    }
}

diaUtil(3);  // Terça-feira
diaUtil(10); // Não é um dia útil válido

See DEMO

Hierarchy:

1. LogicException (extension of Exception)
   • BadFunctionCallException
   • BadMethodCallException
   • DomainException
   • InvalidArgumentException
   • LengthException
   • OutOfRangeException
2. RuntimeException (extension of Exception)
   • OutOfBoundsException
   • OverflowException
   • RangeException
   • UnderflowException
   • UnexpectedValueException