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Date: Wed, 13 Jan 2010 07:01:19 -0600
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Subject: Re: [PHP-DEV] __toString(), __toArray()
From: cpriest@warpmail.net (Clint Priest)



Etienne Kneuss wrote:
> Hello,
> 
> On Tue, Jan 12, 2010 at 11:40 PM, Chris Stockton
> <chrisstocktonaz@gmail.com> wrote:
>> Hello,
>>
>> On Mon, Jan 11, 2010 at 8:32 PM, mm w <0xcafefeed@gmail.com> wrote:
>>> cast is not needed in PHP
>>>
>>> i 'd rather be more interesting in
>>>
>>> class Obj {
>>>     function __catch($data, $type) {
>>>            //$type [ static_method, method, get_property, set_property]
>>>            if (observed &&  $type == set_property && somevalueIsObserved) {
>>>                  $observer->notify("somevalue::valueWillChanged");
>>>                  $this->somevalue = $data['somevalue'];
>>>                  $observer->notify("somevalue::valueDidChanged");
>>>            } else {
>>>                  continue__call();
>>>            }
>>>     }
>>> }
>> What? ...
>>
>>>> Etienne Kneuss wrote:
>>>> This is where operator over-loading would be useful however perhaps only
>>>> explicit casts would make sense here.
>> I beleive adding a __cast(string $type) would be a useful feature for
>> me, very often I have a toArray method defined. I agree with you that
>> due to unexpected edge cases with operator precedence and general type
>> juggling that __cast should only be called on explicit (cast).
>>
>> I.E.:
>> class Int { public function __cast($type) { return 'int' == $type ? 15 : 0; } }
>> $r = new Int;
> 
> This is an exemple where __cast would be very wrong. At the very
> least, it should return a value that is an inhabitant of the requested
> type! Do you really want (bool)new Int() to be Int 0?
> 
> as a result, you have three solutions:
> 1) have the engine issue an error in case the return value is not compatible
> 2) provide a return value for every possible types requested
> 3) throw an exception in case the cast is not handled
> 
> In the end, it looks way more complicated/magic than _simply_ defining
> a toArray method that is used whenever you need an object to be an
> array. You need an explicit cast anyway, so it's (array)$obj vs
> $obj->toArray().

One difference between these two possibilities is that consumers of an 
array parameter could consume an object castable to an array whereas it 
would need to have knowledge that ->toArray() exists in the second scenario.

> 
>> var_dump($r + 1); // 2
>> var_dump((int) $r + 1); // 16
>> var_dump((bool) $r + 1); // 1
>>
>> --
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>>
>>
> 
> 
>