pointer to static member function?

[Malone]

Ok, I have class A with a static function foo.
I want to be able to call this using a pseudo function-pointer as shown below.
Such code works fine on normal functions.

But I get a "call to undefined function A::foo() ..." error when I try the code below.


class A {
function foo($param1, $param2) {
// do stuff
}
}

function bar($param1, $param2) {
// do stuff
}
...


$fptr = 'bar';

$x = 4;
$y = 5;
$fptr($x, $y); # works great!

$fptr = 'A::foo';

$fptr($x, $y); # produces error!

[Justin]

Ok, I have class A with a static function foo.
I want to be able to call this using a pseudo function-pointer as shown below.
Such code works fine on normal functions.

But I get a "call to undefined function A::foo() ..." error when I try the code below.


class A {
function foo($param1, $param2) {
// do stuff
}
}

function bar($param1, $param2) {
// do stuff
}
...


$fptr = 'bar';

$x = 4;
$y = 5;
$fptr($x, $y); # works great!

$fptr = 'A::foo';

$fptr($x, $y); # produces error!




When you call a static function, you dont normally assign it as a var.


<?php

class test {

function test(){
}

function foo($var){
print $var;
}

}

test::foo('test');

?>


Could you clarify what you are trying to do?

[Malone]

Yes, I realize that. Let me explain more clearly what I'm trying to do.

I have a class Customer with a function that I want to use to sort objects of type Customer.


class Customer {
var $firstname;
var $lastname;

# constructor
function Customer($first, $last) {
$this->firstname = $first;
$this->lastname = $last;
}

# compare function
function compare($c1, $c2) { # $c1 and $c2 are objects of type Customer
$result = strcmp($c1->lastname, $c2->lastname);
if ($result == 0) # same last name, compare first names
{
$result = strcmp($c1->firstname, $c2->firstname);
}
return $result;
}
}

# now some where else in my code i have an array of Customers
$customers[] = new Customer('bart','simpson');
$customers[] = new Customer('lisa','simpson');
$customers[] = new Customer('ned','flanders');
#... etc etc

# now I want to sort these Customers
$compareFunction = "Customer::compare"; # assign the compare function
usort($customers, $compareFunction); # this causes an error

# but if i define the compare function outside the class, everything works fine
# compare function
function compareCustomers($c1, $c2) { # $c1 and $c2 are objects of type Customer)
$result = strcmp($c1->lastname, $c2->lastname);
if ($result == 0) # same last name, compare first names
{
$result = strcmp($c1->firstname, $c2->firstname);
}
return $result;
}

$compareFunction = "compareCustomers"; # assign the compare function
usort($customers, $compareFunction); # works great!


So I can make it work, but I would much rather allow each class to have a static member function called "compare" that i can pass to usort(), rather than defining a compare function for each class outside of the class definition. So my question is, is that possible?

[Justin]

Yes, I realize that. Let me explain more clearly what I'm trying to do.

I have a class Customer with a function that I want to use to sort objects of type Customer.


class Customer {
var $firstname;
var $lastname;

# constructor
function Customer($first, $last) {
$this->firstname = $first;
$this->lastname = $last;
}

# compare function
function compare($c1, $c2) { # $c1 and $c2 are objects of type Customer
$result = strcmp($c1->lastname, $c2->lastname);
if ($result == 0) # same last name, compare first names
{
$result = strcmp($c1->firstname, $c2->firstname);
}
return $result;
}
}

# now some where else in my code i have an array of Customers
$customers[] = new Customer('bart','simpson');
$customers[] = new Customer('lisa','simpson');
$customers[] = new Customer('ned','flanders');
#... etc etc

# now I want to sort these Customers
$compareFunction = "Customer::compare"; # assign the compare function
usort($customers, $compareFunction); # this causes an error

# but if i define the compare function outside the class, everything works fine
# compare function
function compareCustomers($c1, $c2) { # $c1 and $c2 are objects of type Customer)
$result = strcmp($c1->lastname, $c2->lastname);
if ($result == 0) # same last name, compare first names
{
$result = strcmp($c1->firstname, $c2->firstname);
}
return $result;
}

$compareFunction = "compareCustomers"; # assign the compare function
usort($customers, $compareFunction); # works great!


So I can make it work, but I would much rather allow each class to have a static member function called "compare" that i can pass to usort(), rather than defining a compare function for each class outside of the class definition. So my question is, is that possible?


Just use Customer::compare($1, $2)

[Malone]

But using Customer::compare($c1, $c2) doesn't work.

For instance:

# same Customer class defintion

# here is an array of Customers
# let's say it's already filled and has 100 elements
$customers;

# now i want to sort the Customers
usort($customers, "Customer::compare");


This raises an error:
"call to undefined function Customer::compare() ..."

I only see this error when I try to do this sort of thing with static class functions.
Regular functions and non-static class functions work just fine.
Is this a limitation of PHP's object-oriented system? Or am I getting the syntax wrong?