php - Query array or object property? -

July 15, 2015

i'm still new oop , simple question, not sure if i'm overthinking this.

let's have simple class following can use instantiate object can generate array:

class gen_arr {     public $arr = array();     public function fill_arr() {      $this->arr["key"] = "value";    }  }  // instantiate object gen_arr $obj = new gen_arr();

now if wanted value of object's array's item, generate array first , echo value like:

$arr = $obj->fill_arr();

echo $arr["key"];

or access object's property directly?

echo $obj->arr["key"]

in actual code property private , there method allows viewing of property array, above simplify question.

are there performance considerations and/or best practices when comes kind of case?

update:

it's still unclear answers if best way generate array property , access array or access property directly (through getter method)

first off, class shared has range of problems:

its sole instance property public , can modified anyone
you have temporal coupling, method fill_arr() needs invoked before accessing the value makes sense

encapsulation

reduce visibility of instance property public private, property can modified object itself, , provide accessor instead:

class gen_arr {     private $arr;      public function fill_arr()      {         $this->arr["key"] = "value";     }      public function arr()     {         return $this->arr;     } }

temporal coupling

remove method fill_arr() , instead initialize property $arr in 1 of following options:

initialize field lazily when accessed first time
initialize field in constructor
initialize field default value
initialize field value injected via constructor

initialize field lazily when accessed first time

initialize field when it's accessed first time:

class gen_arr {     private $arr;      public function arr()     {         if (null === $this->arr) {             $this->arr = [                 'key' => 'value',             ];         }          return $this->arr;     } }

initialize field in constructor

assign value during construction:

class gen_arr {     private $arr;      public function __construct()     {         $this->arr = [             'key' => 'value',         ];     }      public function arr()     {         return $this->arr;     } }

initialize field default value

assign value field directly, works fine if don't need computation:

class gen_arr {     private $arr = [         'key' => 'value',     ];      public function arr()     {         return $this->arr;     } }

initialize field value injected via constructor

if values not hard-coded or otherwise calculated (as in previous examples), , need able instantiate objects different values, inject values via constructor:

class gen_arr {     private $arr;      public function __construct(array $arr)     {         $this->arr = $arr;     }      public function arr()     {         return $this->arr;     } }

accessing , dereferencing values

this seems actual question, answer - of course - it depends!.

let's assume have provided accessor instead of accessing otherwise public field directly:

since php 5.4, following possible:

$object = new gen_arr();  echo $object->arr()['key'];

if still using older version of php, can't , have instead:

$object = new gen_arr();  $arr = $object->arr();  echo $arr['key'];

largely, though, answer question depends on circumstances, , want achieve. after all, readability key maintenance, might make sense introduce explaining variable.

note example, use arrayobject instead:

$arr = new \arrayobject([     'key' => 'value', ]);  echo $arr['key']);

for reference, see:

for example, see:

https://3v4l.org/qvvbm

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