On Fri, Jul 10, 2009 at 01:35:45PM +0300, Ionut G. Stan wrote:
> On 7/10/2009 13:23, Giovanni Giacobbi wrote:
> >On Fri, Jul 10, 2009 at 02:44:52AM +0200, troels knak-nielsen wrote:
> >[...]
> >
> >>For example, instead of:
> >>
> >> function addFive(int $x) {
> >> return $x + 5;
> >> }
> >>
> >>You would simply do:
> >>
> >> function addFive(is_numeric $x) {
> >> return $x + 5;
> >> }
> >>
> >>Since $x is guaranteed to be numeric, it is safe to to arithmetic on
> >>it. No reason to explicitly type cast here.
> >>
> >>
> I like it too. Not only it solves the initial problem, but it also
> allows userland extensions. For example,
> the current patch does not provide checks for callables, but we already
> have is_callable in the core.
Hmmm, but it makes simple cases more complicated and slower. But I do like the
idea of generalising it with a function to handle 'strange' cases.
So, we have 3 syntaxes:
1) function Foo(int $x) {
$x is tested to be integer, if it isn't an error is raised - either by
exception
or just a fatal error.
A problem with this is that it could yeild some surprising results, eg:
Foo(4/2); -- OK
Foo(4/3); -- FAIL since 4/3 yeilds a float
In this last case people would learn to:
Foo((int)(4/3));
2) function Foo((int) $x) {
$x is cast to int, ie converted iff possible - otherwise an error is raised:
int -> int -- OK
float -> int -- OK if in the range for integer
string -> int -- OK iff it is 100% clean:
'10' - OK
'10.1' - OK as string -> float -> int
'10ten' - FAIL/ERROR
etc
What happens when someone tries to use this syntax where he is casting to an
object ?
I suggest that this fails unless the object has a __cast method, in which
case that is invoked:
function Foo((MyObject) $x) {
...
}
class MyObject {
function __cast($x) {
if( ..... )
return new Foo('abcd', $x);
....
}
...
}
3) function Foo(is_int($x)) {
Function is_int is called, an error is raised if it returns false.
--
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT
Lecturer.
+44 (0) 787 668 0256 http://www.phcomp.co.uk/
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