How to destroy an object

Question

As far as I know  which is very little    there are two ways  given    var   new object     Then      Method 1  Set to null  var   null     Method 2  Unset  unset  var      Other better method  Am I splitting hairs here

User · Answer

I would go with unset because it might give the garbage collector a better hint so that the memory can be available again sooner   Be careful that any things the object points to either have other references or get unset first or you really will have to wait on the garbage collector since there would then be no handles to them

User · Answer

May be in a situation where you are creating a new mysqli object    MyConnection   new mysqli  hn   un   pw   db    but even after you close the object   MyConnection- gt close     if you will use print r   to check the contents of  MyConnection  you will get an error as below   Error  mysqli Object  Warning  print r    Property access is not allowed yet in  path to program on line       affected rows    gt   client info    gt   client version    gt                      in which case you can t use unlink   because unlink   will require a path name string but in this case  MyConnection is an Object   So you have another choice of setting its value to null    MyConnection   null   now things go right  as you have expected  You don t have any content inside the variable  MyConnection as well as you already cleaned up the mysqli Object   It s a recommended practice to close the Object before setting the value of your variable to null

User · Answer

A handy post explaining several mis-understandings about this  Don t Call The Destructor explicitly This covers several misconceptions about how the destructor works  Calling it explicitly will not actually destroy your variable  according to the PHP5 doc   PHP 5 introduces a destructor concept similar to that of other object-oriented languages  such as C    The destructor method will be called as soon as there are no other references to a particular object  or in any order during the shutdown sequence   The post above does state that setting the variable to null can work in some cases  as long as nothing else is pointing to the allocated memory

User · Answer

This is a simple prove that you cannot destroy an object  you can only destroy a link to it    var    object   a   gt 1    var2    var   var2- gt a   2  unset  var2   echo  var- gt a    returns     2   See it in action here  https   eval in 1054130

User · Answer

Short answer  Both are needed   I feel like the right answer was given but minimally  Yeah generally unset   is best for  speed   but if you want to reclaim memory immediately  at the cost of CPU  should want to use null     Like others mentioned  setting to null doesn t mean everything is reclaimed  you can have shared memory  uncloned  objects that will prevent destruction of the object   Moreover  like others have said  you can t  destroy  the objects explicitly anyway so you shouldn t try to do it anyway   You will need to figure out which is best for you   Also you can use   destruct   for an object which will be called on unset or null but it should be used carefully and like others said  never be called directly    see   http   www stoimen com blog 2011 11 14 php-dont-call-the-destructor-explicitly   What is difference between assigning NULL and unset

User · Answer

You re looking for unset     But take into account that you can t explicitly destroy an object   It will stay there  however if you unset the object and your script pushes PHP to the memory limits the objects not needed will be garbage collected  I would go with unset    as opposed to setting it to null  as it seems to have better performance  not tested but documented on one of the comments from the PHP official manual    That said  do keep in mind that PHP always destroys the objects as soon as the page is served  So this should only be needed on really long loops and or heavy intensive pages

[php] How to destroy an object?

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