Murray Picton wrote up a blog post today on overloading functions in PHP. Overloading is a useful feature of many languages. Murray gives a nice definition in his post:

Overloading a function is the ability to define a function more than once with a different set of parameters for each one and then when it is called, the version of the function that matches the parameter set will be executed.

so you can define function foo(String $a) and foo(Array $a) and a different version will be called depending on how you call it. But, PHP’s idea of overloading is completely different and not really related.

Hello ladies, look at PHP, now back to Java, now back to PHP. Sadly, PHP’s not Java, but it can look (a bit) like Java if you stop using lady-scented functions and start using method overloading.

I just wanted to get that quote in somehow.

Murray’s solution is to use func_get_args inside your function, and perform some logic to switch execution to a different branch depending on what we find there. Something like:

function foo() {
    $args = func_get_args();
    if(is_string($args)) { /* do some stuff */ }
    else if(is_array($args)) { /* do some stuff */ }
}

This works well enough, but there are a few things I don’t like about it:

1. You have to put all the code into one function, instead of literally overloading multiple functions
2. The “which version am I” code and the actual functionality are intermixed inside the function

I thought an OO solution might mitigate against these things, allowing us to write completely separate functions, but which can be called with the same name, a different one being executed depending on the arguments. I’m not certain my solution is an improvement over Murray’s, but it’s a different approach if nothing else:

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