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Date: Mon, 6 Jun 2016 11:03:58 +0100 (BST)
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To: Dominic Grostate <codekestrel@googlemail.com>
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Subject: Re: [PHP-DEV] Opinion on function/method name overloading
From: derick@php.net (Derick Rethans)

On Mon, 6 Jun 2016, Dominic Grostate wrote:

> As I understand it, using Java-like function overloading in PHP is
> undesirable due to hindrance in readability.

Besides it impacting, readability, it will also create a large impact on 
performance.

Right now, functions (and methods) are looked up by their name only. In 
order to support function overloading, the argument's types also need to 
be taken into account. In C++, it works by mangling function names by 
adding markers for types, such as:

	_ZN4HPHP34c_MongoDBDriverCursor_ni_getServerEPNS_10ObjectDataE

which means:

	HPHP::c_MongoDBDriverCursor_ni_getServer(HPHP::ObjectData*)

But unlike in C++, this needs to be done at runtime, and every time a 
function is called because PHP is dynamically typed, and not statically.

For example:

	myOverLoadedFunction(string $s, long $l, Weather $w)

could be:

	myOverLoadedFunction_s_l_cWeather

or something like that.

Doing these conversions would mean (in the most simple way), that for 
each function call, a string needs to be manipulated to create the 
mangled function name to lookup for in a hash, where right now, they 
only have to be strtolower()'ed (because of case insensivity).

And then you need to do something sensible when *no* types have been 
defined.

cheers,
Derick