BsD BsD - 6 months ago 9
PHP Question

Is there a difference between instantiation with parentheses or without?

What's the difference between these 2 piece of codes?

<?php

$object1 = new User();
//^^
$object1->name = "Hello";
echo $object1->name;
class User {}

?>


And:

<?php

$object1 = new User;
//^
$object1->name = "Hello";
echo $object1->name;
class User {}

?>


I get the same output:

Hello


So is there any difference if I use the parentheses or not in:

$object1=new User;

Answer

The are exactly the same, you can compare opcode of these 2 scripts:

1 script:

$object1=new User();
$object1->name="Hello";        
echo $object1->name;
class User {}

opcode:

line     # *  op                           fetch          ext  return  operands
---------------------------------------------------------------------------------
   3     0  >   FETCH_CLASS                                   4  :0      'User'
         1      NEW                                              $1      :0
         2      DO_FCALL_BY_NAME                              0          
         3      ASSIGN                                                   !0, $1
   4     4      ASSIGN_OBJ                                               !0, 'name'
         5      OP_DATA                                                  'Hello'
   5     6      FETCH_OBJ_R                                      $5      !0, 'name'
         7      ECHO                                                     $5
   6     8      NOP                                                      
         9    > RETURN                                                   1

2 script:

$object1=new User;
$object1->name="Hello";        
echo $object1->name;
class User {}

opcode:

line     # *  op                           fetch          ext  return  operands
---------------------------------------------------------------------------------
   3     0  >   FETCH_CLASS                                   4  :0      'User'
         1      NEW                                              $1      :0
         2      DO_FCALL_BY_NAME                              0          
         3      ASSIGN                                                   !0, $1
   4     4      ASSIGN_OBJ                                               !0, 'name'
         5      OP_DATA                                                  'Hello'
   5     6      FETCH_OBJ_R                                      $5      !0, 'name'
         7      ECHO                                                     $5
   6     8      NOP                                                      
         9    > RETURN                                                   1