doumouyi4039
doumouyi4039
2018-05-11 13:29

具有许多属性的不可变对象

已采纳

I've got a class that I want to make immutable but that class has a lot of properties.

<?php

class Gameworld {

    /** @var string */
    private $name;

    /** @var string */
    private $type;

    /** @var bool */
    private $is_online;

    /** @var int */
    private $online_players;

    /** @var int */
    private $online_players_record;

    /** @var string */
    private $description;

    /** @var string */
    private $location;

    /** @var \DateTime */
    private $created_at;

}

How to create such object? When I introduce public function __construct() with all those properties it will get bloated. If I introduce setters it won't be immutable anymore.


EDIT: I was thinking about making setters but ones that could be only used once. Thanks to that I won't have bloated constructor but for some reason it seems not like a good idea. Something like:

class Gameworld {

    ... old properties ...

    /** @var array */
    private $used_setters = [];

    public function setName(string $name){
        if(in_array('name', $this->used_setters)){
            throw new ImmutableException('Class Gameworld is immutable.');
        }

        $this->name = $name;
        $this->used_setters[] = 'name';
    }

}
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2条回答

  • douci1677 douci1677 3年前

    I would use __set() magic method to check if the value is set else I would throw an exception:

    class Gameworld {
    
        /** @var string */
        private $name;
    
        /** @var string */
        private $type;
    
        /** @var bool */
        private $is_online;
    
        /** @var int */
        private $online_players;
    
        /** @var int */
        private $online_players_record;
    
        /** @var string */
        private $description;
    
        /** @var string */
        private $location;
    
        /** @var \DateTime */
        private $created_at;
    
        public function __set($property, $value)  
        {  
            if (property_exists($this, $property)) {  
                if(is_null($this->$property)){
                    $this->$property = $value;
                    return $this;
                }
                throw MyCustomException();
            }
            throw UndefinedClassVariableException();
        }
    }
    

    A basic usage would be:

    $x = new Gameworld();
    $x->name = "OK";
    $x->is_online = true;
    $x->name="Exception";
    

    P.S: Exceptions must extend the base exception class or you could trigger or log an error, depends on what you want

    P.S.S: An alternative sollution would be to use __call() method and check if the value is null

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  • duandi2853 duandi2853 3年前

    I would suggest passing properties as an array argument like

    __construct( array $properties )
    {
      $this->property = $properties['property'];
      ....
    }
    
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