Functions 'Sumbmitting' back to themselves

Urban_Roughneck · March 9th, 2005, 10:51 AM

I have a page that uses a switch to determine which of a number of functions is called and placed in a div. This gives the effect of that div being multifunctional.

However some of the functions contain forms or other links that require the function to post info back into itself.

Is this possible?

colin.horne · March 10th, 2005, 06:32 PM

Please elaberate a bit (I'm unsure what you're wanting).

In the mean time, you may wish to read this: http://uk.php.net/manual/en/function.call-user-func.php

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richard.york · March 12th, 2005, 09:05 PM

I beleive he is talking about calling a function recursively, as in:

function foo()
{
    foo();
}

The above would create an infinite loop, but this is valid. Recursive functions tend to make your head spin. But they work the same as a normal function does, in that, you include a return; statement to pass control back to the calling code. In this case the calling code could be the same function, in which case you control those nested calls with return statements until the whole thing is finished with whatever it is doing. Does that make sense?? Here is an example.

function foo($bar = false)
{
   if ($bar)
   {
       // This value is returned to the recursively called foo
       return 'Hello, world!';
   }
   else
   {
       // A return here will return the value returned by the recursively called foo()
       // Otherwise that returned value would be lost to oblivion.
       return foo(true);
   }
}

echo foo();

The above limits the recursive call on foo to only once, on the second call $bar is true and the value 'Hello, world!' is returned and output.

I've seen some benchmarking that indicates recursive functions can really slow down a script, in my own experience whenever I've needed one however, it hasn't been noticable.

Regards,
Rich

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colin.horne · March 12th, 2005, 09:21 PM

Hi Richard

> I've seen some benchmarking that indicates recursive functions
> can really slow down a script, in my own experience whenever
> I've needed one however, it hasn't been noticable.

I _think_ this is correct:

When you call up a function, it adds your current memory address to the stack, so once the function has finished, the processor knows where to read the next command from. If you call functions recursively then it can fill up the stack.

Nowerdays we're often spoilt with a huge amount of memory to play around with, but I hear that 'Stack overflow' errors were very common back in the olden days when memory was scarce.

Cheers

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Please contact me at:
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Urban_Roughneck · March 14th, 2005, 12:50 PM

Sorry if I wasn't clear what I wanted.

I have an index page that has a switch on it:

Code:

switch ( $transform )
{
  case "test":
      include ("logticket.php");
    logticket();
    break;
  case "test2":
      include ("tableselect.php");
    tableselect();
    break;
  case "test3":
    include ("udateticket.php");
    udateticket($id, $update);
    break;
  case "t_id":
    $query = "SELECT * FROM `ticket` WHERE ticket_status LIKE '$status' ORDER BY ticket_id LIMIT 40";
    include ("tableselect.php");
    tableselect();
    break;
default:
    echo "<div id = content2>";
    echo "This is where the operations that you can perform will appear. You are currently seeing this text because ";
    echo "you have not selected an option yet.";
    echo "</div>";
    break;
}

The functions called in this switch determine what appears in a particular div. Hence this 'box' appears to do many things. One of the functions contains a form and I wanted to reload that function, much like you can submit info back to a page by using $_SERVER['PHP_SELF'] I wondered if it was possible to give a value back to a fuction.

So if foo was to accept $a and $b but it gets the result of $b AFTER being run.

I'm not sure I'm making sense still but I hope I'm making things a little clearer.