call methods of an object declared outside of a function...

[b14speedfreak]

Hi All,

 

My appologies in advance.  I am pretty sure that this has probably been answered before by someone...but for the life of me I carn't find the answer in any forums. 

 

My basic question is this.  Can you create an object at the beginning of a script, and then call its methods from within functions?

 

I have coded the following:

 

<?php

///import classes to use
require "booking_form_gui.php";

$booking = new booking_form_gui();

function _booking_form($form_state){
    
    ///$booking = new booking_form_gui();
   
    return $booking -> date_selection();         <----------this line causes the error I guess


}

 

The problem is that when I run this code, I get an error message similar to the following:

 

Fatal error: Call to a member function date_selection() on a non-object in /var/www/drupal_6/sites/default/modules/booking_system/booking_form/booking_form.module on line 127

 

Anyone any ideas how I could get round this? 

 

Thanks,

 

Mark.

 

[Jessica]

read about "variable scope".

 

You need to either pass the object into the function, or make it global.

[ManiacDan]

Generally using globals is bad form, if you need something inside a function, pass it into that function. 

 

Also: Variable Scope

 

-Dan

[Jessica]

Generally using globals is bad form, if you need something inside a function, pass it into that function. 

I agree, but there are a few cases where I'd do it.

Like with a DB object or something. It depends on the script.

[ManiacDan]

Yeah, procedural code with global DB objects generally rely on globals because it's not considered "lazy" there for some reason.  I still dislike it, but I haven't written procedural code in years, so whatever floats your boat. 

 

Either way, OP needs to read that link.

 

-Dan

[b14speedfreak]

Hey all,

 

Thanks for the replys.  Sorry its taken me a while to reply. 

 

I hadn't thought about just passing it into the function.  But I am still having issues with this.  I carn't seem to get the execute the objects methods. 

 

For example I tried doing this:

 

///import classes to use
require "booking_form_gui.php";

$booking = new booking_form_gui();

function _booking_form($form_state){
    
    $booking = $GLOBALS['booking'];

    
    $form = $booking -> date_selection();

    return $form;
}

 

However this doesn't seem to work.  I am pretty sure I am missing something here. 

 

I also tried passing it into the function:

 

///import classes to use
require "booking_form_gui.php";

$booking = new booking_form_gui();
function _booking_form($form_state, &$booking){
    
    ///$booking = new booking_form_gui();
    $form = $booking -> date_selection();

    return $form;
}

 

Real appologies for being slow...

 

Thanks in advance for any subsequent posts,

 

Mark.

[Jessica]

What about the code where you call that function?

[b14speedfreak]

ok, so I have one script that looks like the following:

 

///import classes to use
require "booking_form_gui.php";

$booking = new booking_form_gui();
function _booking_form($form_state, &$booking){
    
    ///$booking = new booking_form_gui();
    $form = $booking -> date_selection();

    return $form;
}

 

Then the object that I create $booking I hoping to create out of the following code from another class file (the one that I included).  The code for this is:

 

class booking_form_gui {




/**
*  Date Selection Form
* @return string
*/
function date_selection (){

    ///creat $booking as a booking object!
    ///$booking = new booking();

    ///form to allow the the users to select which dates that they want

    ///form input widgets
    $form['start_date'] = array(
        '#type' => 'date_popup',
        '#title' => t('The Start Date'),
        '#date_format' => 'd/m/y',
        '#required' => TRUE,
    );

    ///$form['start_date']['#prefix'] = t("This form will allow to book a "
       ///     ."Non Residential Sailing Holiday"
          ///  ." <br><br>Firstly you need to select a start and end date "
           // ."that you wish to travel on.  After this you will be able to "
           // ."reivew the prices and the places available and alter the dates "
           /// ."if you require.");

    $form['end_date'] = array(
        '#type' => 'date_popup',
        '#title' => t('The End Date'),
        '#date_format' => 'd/m/y',
        '#required' => TRUE,
    );

    $form['add'] = array(
    '#type' => 'submit',
    '#value' => 'Check Prices and Places Available.',
    ////'#submit' => array('add_new_date_form_submit'),
    );

    return $form;
}

 

I should probably point out at this point, that this for a Drupal Module.  I didn't think that it made much difference.  But hopefully it will make some sense?

 

Thanks again for the help

 

Mark.

[b14speedfreak]

...It works fine if I create the object in the function.  However I figured that it would be better if I could create the object out side of a function, so that other functions in my script could use the methods and set the attributes...if that makes sense?

 

 

[Jessica]

No where are you calling "_booking_form"

[b14speedfreak]

...ok so that get a little specific to drupal I guess...However I can see where you are going with that....

 

Ok the full execution would look like this :

 

<?php
/**
*     <h1>The Actual Booking Form</h1>
*
*This is the actual booking form module that the cleints will use in order to
* book non-residential sailing courses with Minorca Sailing.
*
* Author = Sparky Mark.
*/

///import classes to use
include "booking_form_gui.php";

$booking = new booking_form_gui();

function booking_form_menu(){
///create a $pages array
    $pages = array();

    ///put in the pages

    ///the date selection form
    $pages['the_booking_form'] = array(
        'title' => t('Non Residential Booking Form'),
        'page callback' => 'the_booking_form',
        'access arguments' => array('view non residential booking form'),
        'description' => t('This is the booking form that the clients will use.'),
        'type' => MENU_CALLBACK
    );

}

function the_booking_form(){
    ///seen as its a form we have to call it as one
    return drupal_get_form('_booking_form');
}

function _booking_form($form_state, &$booking){
    
    ///$booking = new booking_form_gui();  
    $form = $booking -> date_selection();

    return $form;
}

 

Ok, so the I can see what you where getting at, I hadn't actually passed the object into the function anywhere!  Ok not sure how this will work to be honest.  Ok I am guessing this is exactly how it works...but I will admit I could be wrong...

 

...So when a request is made to the page 'http://192.168.0.10/drupal_6/?q=the_booking_form' the drupal engine searches for a function called 'the_booking_form'.  For whatever, not exactly sure 100% why but you then have to tell it that its a form its dealing with (drupals quite specific about the way it likes to handle forms...but does have some really cool features).  So it then calls the function 'the_booking_form', which in turn tells drupal that its not a PHP page but a form that its calling...it then calls the function '_booking_form'.

 

Ok with me so far?

 

I can get it work just fine, if I create my booking_form_gui object in the _the_booking_form function.  The problem I have with doing that, once outside of that function I loose all of the functionality of that object - and that something that I would rather keep if I could.

 

Hope that it makes sense what I have asked.  I tried using the <i>globals $booking</i> idea, but I couldn't get it to work at all - I just seemed to get compliation errors.  When I tried using the $GLOBALS['booking'] idea, I hit the same problem as I have now. 

 

The one thing that I have found hard about drupal is that its procedural programming, and really I find it easier to program using Object Orientated - my Java background probably doesn't help matters...

 

...thanks again for all the replies...

 

Mark.

 

 

 

 

[b14speedfreak]

If I change the code in the _booking_form module to this:

 

function _booking_form($form_state){

    global $booking;

    return $booking ->date_selection();

}

 

Then I get the following error on execution:

 

Fatal error: Call to a member function date_selection() on a non-object in /var/www/drupal_6/sites/default/modules/booking_system/booking_form/booking_form.module on line 127

 

So I don't see how using the global command could work in this case. 

 

Thanks again,

 

Mark.

[Jessica]

Try putting the object in a session.

[b14speedfreak]

...hey that works a treat!

 

Thanks for that.  I remoded the code to look like the following:

 

///import classes to use
include "booking_form_gui.php";

$booking = new booking_form_gui();

$_SESSION['booking'] = $booking;

function booking_form_menu(){

    ///create a $pages array
    $pages = array();

    ///put in the pages

    ///the date selection form
    $pages['the_booking_form'] = array(
        'title' => t('Non Residential Booking Form'),
        'page callback' => 'the_booking_form',
        'access arguments' => array('view non residential booking form'),
        'description' => t('This is the booking form that the clients will use.'),
        'type' => MENU_CALLBACK
    );

}

function the_booking_form(){
    ///seen as its a form we have to call it as one
    return drupal_get_form('_booking_form');
}

function _booking_form($form_state){

    $booking = $_SESSION['booking'];

    $form = $booking ->date_selection();

    return $form;

}

 

And hey presto I get my nice looking drupal form 

 

Thanks again for bearing with me.  I really appreciate it.

 

Mark 

[Jessica]

Awesome!