object lifetime

fxpepper

Hello,

I have a few questions about an object.

So i have a checkbox which is supposed to turn on an object if checked.

I have something like this:

class my_object {

  public__construct {
	add_action ('init' , 'my_action_function' ); // wordpress hook
        add_filter('filter_name' , 'my_filter_function') ;  // wordpress hook
   }

  function my_action_function() {
    // function stuff
 }

  function my_filter_function() {
   // function stuff
  }

  functions...

}

// check if checkbox is checked
if ($checkbox == 'checked') {
	$object_a_test = new my_object;
} else {
	return;
}

so my question is, says it's checked..the object gets instantiated, right? Then say the user decides to uncheck and turn it off...are the action which are used in the construct automatically removed/destroyed? It seems to be working like I expect but i just want to make sure these functions/hooks aren't there in the background.

I was thinking i should maybe handle this in the destructor - which is only called when the object is destroyed right? Or make sure this are explicitly removed another way? Or is this done automatically just by unchecking the checkbox (b/c it fails the if statement above) ?

also, this object (when turned on) is essentially persisting until the user turns it off (through the checkbox), right?

hope this make sense...

thanks

NogDog

Assuming this is a web app, the object only persists until the script completes (or sooner if explicitly destroyed or the compiler determines it is no longer in scope and optimizes it away).

So if we assume a typical web app flow:

User clicks checkbox and submits request to server via HTTP.
Server receives HTTP request, starts PHP script, which creates object, does stuff with it, then destroys object when the script ends, and sends output to user via HTTP.
User unchecks the checkbox and submits another HTTP request to the server.
Server receives that request, fires off PHP script again from the top, sees that the checkbox is not checked, so the object is never instantiated this time.

fxpepper

Thanks NogDog for your response.

So regarding this note:

NogDog;10998282 wrote:
2. Server receives HTTP request, starts PHP script, which creates object, does stuff with it, then destroys object when the script ends...

Now just because the object is destroyed, I want to make sure these settings are saved (settings are set up through constructor hooks/functions). So is it safe to 'assume' that these ARE saved (for web app), until this checkbox becomes unchecked?

thanks

NogDog

Nope, they are not saved unless you explicitly save them somewhere that will persist between invocations of the PHP script. Typically this is done via PHP session variable or in the database (or via a custom session-handler using the database 😉 ).

traq

fxpepper;10998285 wrote:
Now just because the object is destroyed, I want to make sure these settings are saved (settings are set up through constructor hooks/functions). So is it safe to 'assume' that these ARE saved (for web app), until this checkbox becomes unchecked?

I'm not sure what you mean by "I want to make sure these settings are saved," but I suspect the answer is "no."

Whatever your object's methods did is not "undone" when the object is destroyed. however, unless you explicitly "saved" whatever settings you're talking about (in a database/text file/$_SESSION/whatever), then no, they're gone.

Not because the object is gone, but because the script ended and you've moved on to a new (different!) HTTP request now.

[edit] whup, sorry for the overpost, NogDog [/edit]

fxpepper

traq;10998288 wrote:
I'm not sure what you mean by "I want to make sure these settings are saved," but I suspect the answer is "no."

Whatever your object's methods did is not "undone" when the object is destroyed. however, unless you explicitly "saved" whatever settings you're talking about (in a database/text file/$_SESSION/whatever), then no, they're gone.

Not because the object is gone, but because the script ended and you've moved on to a new (different!) HTTP request now.

okay, i think that is what i needed to know. I knew the checkbox's value was saving but i wasn't sure if the functions' actions were...

However, it does seem that they must be saving these settings in the db because it's still running these settings. I will see if i can figure out how to know for sure.

thanks everyone.

traq

I still don't know what you mean by "settings." Is this something that you're developing yourself, or are you trying to modify another script (or CMS)?

Do your methods save info to the database (or, are they "supposed" to)? Have you checked your DB directly to see if the info is saved or not?

fxpepper

I guess i mean the checkbox setting and other data that is saved in the DB (like adding the filter, etc). I am working with a CMS.

traq

okay - in that case, the answer is "if you saved it, then it's saved."

So, if your methods save the setting to the DB successfully, then it will still be saved after the object is destroyed.

paddysmith

I have newbie,

your post is boost of interesting....

fxpepper

I see, okay...thanks again!