Fatal error: Call to a member function on a non-object

BigBadKev

Hi,

I am new to php progamming and having problems with functions passing to class's and I think its a scope problem.

Free free to critque my code at will as i want to learn.

What I am doing is calling a debug class that writes to a debug.txt output file, and I have to declare the variable as a global in each function, can I use a superglobal variable so it knows that it is a debug class without havinng to re-declare it in every function in php? here is a sample of the code and the class

include("c:\\debug.php");

$d = new debug;

//if I set global $d here and do not set global $d in 
//any function it fails with the error message "Fatal error: Call 
//to a member function on a non-object", this does make sense
//to me as how can the function ever know the object,
//so is there a way to declare global $d so its like a super global?


function newbie()  {
  //this works...
  global $d
  $d->s("function newbie");
  $var1 = "hello";
  $d->s("v = " . $var1);
  $d->s("end function newbie");
}
function beginner()  {
  //this works...
  global $d
  $d->s("function beginner");
  $var2 = "world";
  $d->s("v = " . $var2);
  $d->s("end function beginner")
}

//debug.php
//The Class- this all works and really isnt the issue with the class
class debug {
  function debug()  {  

    ...create the file, open for writing etc etc
  }
  function s($debug) {
    ...writes what ever is passed to it...
  }
}

These two files are the only two used as this is just a tutorial for me to learn php so there is no sessions etc set up, any help goes beyond thankyou as i am stumped as to what/which way to go, I had a look at serilise/unserilise but this seems really clumsy or am I missing something here, thanks guys.

BBK

sdjensen

I think you do change the functions to use $this instead of $d like

$d = new debug; 

function newbie()  { 
  //this works... 
  $this->s("function newbie"); 
  $var1 = "hello"; 
  $this->s("v = " . $var1); 
  $this->s("end function newbie"); 
} 
function beginner()  { 
  //this works... 
  $this->s("function beginner"); 
  $var2 = "world"; 
  $this->s("v = " . $var2); 
  $this->s("end function beginner") 
} 

... rest of code

BigBadKev

Hi sdjensen

I tried that and got the same error, the "$this->" is used more in the class itself. These funtions are not in the class but on a separate page.

you were thinking something like this below?

class debug { 
  function debug()  {   

    ...create the file, open for writing etc etc 
  } 
  function s($debug) { 
      $this->x($debug);
  } 
  function x($debug) {
      .....do something....
  }
}

That was my fault and i should have stated it a bit more clearly, there is two seperate php pages.
One has the function calling the class and the other is the class itself.

please keep the ideas flowing as this is a killer code bug that I have found quite hard to get info on.

BBK
😃

ahundiak

Sadly, there is no means for a user to create their own super globals. It would be nice. So every function that accesses your debug object does indeed need a:
global $d;

But I think you will find yourself using classes more and more. And in this case, you will end up storing a reference to the debug class in each object which in turn means that the internal methods will have access to it without the need for a global.

BigBadKev

Hi ahundiak,

Thanks for helping me, I am truly surprised that this is the case and I really did believe there would be a way to store this object through either a super global or a session variable, just another question, is it possible to serialise the object, insert it into a DB, retrieve it later and unserialise it?, and do you know where I can get info on passing objects in php?.

I have followed php since php3 and read the forums regularly and have noticed a ton of people having this error message with slight variations of the same theme – passing objects.

Thanks again.

BBK
😃

ahundiak

Serializing an object is no big deal. Skim through the comments in the "Classes and Objects" chapter in the manual for some examples and discussion of some restrictions.

BigBadKev

Hi again

So just to clarify: to pass from a function to a class I have to make the var global? so in theory I could end up with many global calls from a singular function if it wanted to use many different class objects?

So like below if they all were different class calls....

global $d, $e, $f, $g, etc etc

Does this not lead to many many global vars “swishing” around? Or is there another way to tackle this global call problem?

Sorry if I appear completely stupid…

BBK
😃

HalfaBee

The global $d only makes $d available to the function.
It is effectively the same as this code.

function x()
{
$d = $GLOBAL['d'];

// do stuff to $d

$GLOBAL['d] = $d;
}

BigBadKev

Hi HalfaBee and others

Your function below

function x() {
  $d = $GLOBAL['d']; 
  // do stuff to $d 
  $GLOBAL['d] = $d; 
}

Could I re-write it like this (remember I am a newbie so I may not be perfectly correct)?

$d = new debug;
$d = $GLOBAL['d'];

function x()  {
  $d->s(“function x”);
   //do something
  $d->s(“end function x”);
}

really do appreciate it guys.

BBK
😃

HalfaBee

No you can't do that.

Just put

global $d;

in the function.

HalfaBee

BigBadKev

Hi,

thanks all for your help and quick reply's.

For newbies like me it is a real source of help.

BBK
😃