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Date: Thu, 12 Feb 2015 18:22:33 +0100
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Subject: AW: [PHP-DEV] [VOTE] Scalar Type Hints
From: php@tutteli.ch ("Robert Stoll")

Hi Fran=C3=A7ois,

> -----Urspr=C3=BCngliche Nachricht-----
> Von: Fran=C3=A7ois Laupretre [mailto:francois@tekwire.net]
> Gesendet: Donnerstag, 12. Februar 2015 18:01
> An: 'Robert Stoll'; 'Nikita Nefedov'; 'Andrea Faulds'
> Cc: 'Pavel Kou=C5=99il'; 'PHP Internals'
> Betreff: RE: [PHP-DEV] [VOTE] Scalar Type Hints
>=20
> Hi Robert,
>=20
> > De : Robert Stoll [mailto:php@tutteli.ch]
> >
> > There are several programming languages which do support dynamic
> > typing and method overloading somehow (Clojure, Erlang, Prolog, =
Cecil
> > and certainly more).  Most of them use a multi-method approach and I
> > think if PHP would introduce function/method overloading, then such =
an
> > approach would be appropriate. Right now, I need to implement the
> > dynamic dispatching quasi myself which might be more verbose but is
> > also more cumbersome (and uglier IMO). Consider the following =
(fictional example):
>=20
> We all agree on the interest of polymorphism on object classes, even =
if your example could be solved with specialized
> logger classes, but the question was about polymorphism on different =
scalar types, which is much more problematic in PHP,
> even using strict scalar typing.
>=20
> Cheers
>=20
> Fran=C3=A7ois

OK, maybe I went a little bit off topic due to the booted discussion =
about method overloading which did not cover all aspects IMO.  So back =
to scalar type hints:
I do not really see how num would be a problem or polymorphism in =
general. I am not really aware of memory management of PHP but I guess =
it is not optimised for fixed-sized integers or is it?
If not, then it does not really matter whether a parameter holds an int, =
a float or a BigInt, allocation is dynamic anyway I suppose. Or what =
problems do you see here?

Maybe you are referring to Pavel's example:

> the issue I see with it is that bar() requires float, but foo() just =
number and doesn't convert it to the required type. The most =
unpredictable thing is that it will work half of the time and half of =
the time it will just throw errors

The same applies for the following code

class Foo{}
class Bar{}

function foo(Foo foo){
  bar($foo);
}
function bar(Bar bar){
   //..
}

and we still agree upon that polymorphism is the right way to go since =
it allows more expressive code with a certain "safety". If you want full =
flexibility, then rely on dynamic typing only and if you want some =
safety then use type hints.  I do not see a special case here - =
polymorphism for scalar types is nothing new