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Date: Mon, 11 Jan 2010 21:17:53 -0600
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Subject: Re: [PHP-DEV] __toString(), __toArray()
From: cpriest@warpmail.net (Clint Priest)


Etienne Kneuss wrote:
> Hello,
> 
> On Mon, Jan 11, 2010 at 7:31 PM, Clint Priest <cpriest@warpmail.net> wrote:
>> I know there's been requests to add a __toArray() and most of the arguments
>> against it is that there are too many magic functions already.  I just
>> thought I'd propose an alternative that would satisfy all of them.
>>
>> Why not a __cast($Type) magic function?
> 
> I'd advance two reasons against this idea:
> 
> 1) It's more self-explanatory to explicitly call the appropriate
> converting method, enough with implicit madness!
> 
> 2) For some operations, you'd have to know the types in advance before
> knowing what operations needs to be performed:
> 
> $obj1 + 2;
> 
> Now what __cast should be called? Int? Float?

Wouldn't it make sense to be an integer since its being added to an integer?

> 
> Also, what about $obj1 + $obj2: Int? Float? Array?

This is where operator over-loading would be useful however perhaps only 
explicit casts would make sense here.

> 
> Another example: str_replace($obj1, "bar", "foo"); what to call?
> __toString or __toArray? str_replace accepts both.

This is an interesting situation, could be resolved by attempting a 
__cast('array') followed by a __cast('string') if the first call was 
rejected (false, exception or something).

> 
> IMHO it would only make sense to invoke methods on explicit casts
> only, otherwise it will just be a mess with PHP's current type
> juggling. But, as we seen with __toString, limiting the field of
> application was annoying (and it was later extended to nearly all
> string usages).

I would agree with this as well, only called during explicit casts.

> 
> So, what will it be? Inconsistent and Confusing or Limited and Annoying?
> 

One other alternative, probably not as easy would be to pass multiple 
types to cast, much the way the Accepts: HTTP header does, providing a 
list of possible cast types, in the preferred order.

One could even implement an interface such as:

interface Castable {
    function GetCastableTypes();
}

or some such.

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> 
> 
>