Overloaded functions and function pointers in PHP?

[Peter Salzman]

Hi all,

Since PHP is a (weakly) typed language, is it possible to overload functions
based on the type of their argument?

Also, are there function pointers in PHP?
Here's why I'm asking. Consider these two function:
function foo( $arg ) { echo "foo $arg foo\n"; }

function bar() { echo "barfoo"; }
I'd like to be able to do this:

foo('hello');
foo(&bar());

to produce this:

foo hello foo
foo barfoo foo

Is this at all possible (and convenient!) with PHP?

Thanks!
Pete

[Oli Filth]

Peter Salzman said the following on 10/09/2005 17:21:

Hi all,

Since PHP is a (weakly) typed language, is it possible to overload functions
based on the type of their argument?
No. But there are default arguments, and variable-length argument lists
(PHP 4+).
See http://www.php.net/manual/functions.arguments.php.

Also, are there function pointers in PHP?
No. But there are functions like call_user_func(), which make them
somewhat redundant.
See http://www.php.net/call_user_func.

Here's why I'm asking. Consider these two function:
function foo( $arg ) { echo "foo $arg foo\n"; }

function bar() { echo "barfoo"; }
I'd like to be able to do this:

foo('hello');
foo(&bar());

to produce this:

foo hello foo
foo barfoo foo

How about:

function foo($arg)
{
echo "foo $arg foo\n";
}

function bar()
{
return "barfoo";
}

foo(bar());
--
Oli

[Peter Salzman]

Oli Filth <ca***@olifilth.co.uk> wrote:

Peter Salzman said the following on 10/09/2005 17:21:

Here's why I'm asking. Consider these two function:
function foo( $arg ) { echo "foo $arg foo\n"; }

function bar() { echo "barfoo"; }
I'd like to be able to do this:

foo('hello');
foo(&bar());

to produce this:

foo hello foo
foo barfoo foo

How about:

function foo($arg)
{
echo "foo $arg foo\n";
}

function bar()
{
return "barfoo";
}

foo(bar());

The function argument seems to be executing before the call to foo is made.
In my own code, I'm getting the equivalent of:

barfoo foo foo

rather than

foo barfoo foo
Pete

[Oli Filth]

Peter Salzman said the following on 10/09/2005 17:45:

Oli Filth <ca***@olifilth.co.uk> wrote:

Peter Salzman said the following on 10/09/2005 17:21:

Here's why I'm asking. Consider these two function:
function foo( $arg ) { echo "foo $arg foo\n"; }

function bar() { echo "barfoo"; }
I'd like to be able to do this:

foo('hello');
foo(&bar());

to produce this:

foo hello foo
foo barfoo foo

How about:

function foo($arg)
{
echo "foo $arg foo\n";
}

function bar()
{
return "barfoo";
}

foo(bar());

The function argument seems to be executing before the call to foo is made.
In my own code, I'm getting the equivalent of:

barfoo foo foo

rather than

foo barfoo foo

That's because your bar() is echoing; mine is returning.

--
Oli

[Chung Leong]

Peter Salzman wrote:

Since PHP is a (weakly) typed language, is it possible to overload functions
based on the type of their argument?
Kind of. You can always check the type of argument that's actually
passed with one of the is_* function and have the function behave
differently (e.g. array vs. scalar).
Also, are there function pointers in PHP?
Kind of. In PHP, functions are referenced by name. If you do $func()
and the variable $func contains the name of a function, it will be
called.
I'd like to be able to do this:

foo('hello');
foo(&bar());

to produce this:

foo hello foo
foo barfoo foo

I don't think that's doable in any language.