Method Overloading in PHP

Question

Excuse my newbishness. While working on an ASP.Net based website, I remember seeing some methods in which could accept a different number of arguments. Specifically, they would do different things, depending on the number of parameters passed to them.

For example:

Email.sendEmail(address,subject,body);

would do something different to:

Email.sendEmail(address,bccaddresses,subject,body);

Is it possible for methods in PHP to do something similar? What is this thing called? Or have I just totally misremembered something?

This is called method/function overloading. PHP does not have this natively without hacky workarounds involving func_get_args or confusing variable names. Boo :-( — cmbuckley
– cmbuckley, Commented Feb 17, 2012 at 16:36
@cbuckley PHP seems to have an even better way of overloading . . . stackoverflow.com/a/9332030/798818 — Mob
– Mob, Commented Feb 17, 2012 at 16:37
Overloading != optional parameters. This allows for different arity but checking of data types must be handled in the function rather than explicitly defining multiple function signatures. — cmbuckley
– cmbuckley, Commented Feb 17, 2012 at 16:38
@cbuckley That's it! I thought it was called "overloading", but I couldn't find a good example of it, for some reason. — Chuck Le Butt
– Chuck Le Butt, Commented Feb 17, 2012 at 16:40
I would agree with Tim on this one, as it also allows for extensibility without breaking E_STRICT compliance. — cmbuckley
– cmbuckley, Commented Feb 17, 2012 at 17:28

cmbuckley · Accepted Answer · 2012-02-17 17:26:21Z

3

function sendEmail($address, $bccaddresses, $subject, $body=NULL) {
  if ($body === NULL) {
     $bccaddresses=""; //or whatever default you want
     //shift arguments:
     $subject = $bccaddresses; $body = $subject;
  }
}

edited Feb 17, 2012 at 17:26

cmbuckley

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answered Feb 17, 2012 at 16:56

Karoly Horvath

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2 Comments

cmbuckley Over a year ago

+1 This was what I was referring to as confusing variable names :-) Works well but can be hellish without good documentation!

Chuck Le Butt Over a year ago

+1 This does look like it could work, but I'll go with your recommendation, cbuckley.

Tim · Accepted Answer · 2012-02-17 23:56:40Z

2

You could use an associative array as the argument, and make use of extract().

function sendMail($opts){
    extract($opts, EXTR_SKIP); // EXTR_SKIP prevents extract from overwriting anything already in the symbol table
    if(isset($bccaddresses)){
        // do something with the bcc addresses
    }
    echo "sending some mail to $to with subject $subject";
}

sendMail(array("to"=>"[email protected]", "subject"=>"Hi!"));

This lets you pass in the arguments as named values, with optional values as you see fit.

edited Feb 17, 2012 at 23:56

answered Feb 17, 2012 at 17:11

Tim

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Comments

lorenzo-s · Accepted Answer · 2012-02-17 16:33:43Z

1

You are searching for func_num_args() and func_get_args().

See also related examples, it shows you how to do exactly what you need.

answered Feb 17, 2012 at 16:33

lorenzo-s

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Comments

Tim · Accepted Answer · 2012-02-17 16:34:07Z

1

In PHP, you set default values for functions.

function myFunc($val1 = 1, $val2 = 2, $val3 = 3){
    echo "$val1 $val2 $val3";
}


myFunc();     // outputs 1 2 3
myFunc(5);    // outputs 5 2 3
myFunc(8, 1); // outputs 8 1 3

answered Feb 17, 2012 at 16:34

Tim

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