RE: [PHP-DEV] [Draft RFC] Object Casting and Assignment Handlers
As much as I would love to have __castTo() and __assign() I have to agree with Stas here that it
fundamentally changes the mechanics of if($object) and unfortunately turns that simple if statement
into a possible hour long hunt to find the code that is doing the damage, if it is even considered a
possibility by someone reading the code.
For the record, I really have only ever needed something like __toArray() so that objects
implementing ArrayAccess could be passed to array internal functions.
I am interested in object natives though, which this is leading in the direction of.
-Clint
-----Original Message-----
From: Stas Malyshev [mailto:[email protected]]
Sent: Wednesday, February 29, 2012 1:48 AM
To: Anthony Ferrara
Cc: [email protected]
Subject: Re: [PHP-DEV] [Draft RFC] Object Casting and Assignment Handlers
Hi!
> Hey all,
>
> I've created a draft version of the RFC for implementing __castTo()
> and __assign():
>
> https://wiki.php.net/rfc/object_cast_magic
I think having cast method may have merits, though use cases where objects need to be converted to
scalars that aren't string are very limited, and cases where they need to do so transparently
are almost non-existent. I think what outlined in the RFC is a backdoor operator overloading,
through rather complex and unobvious magic. My opinion is that outside of very limited number of
cases (such as implementing complex numbers or matrix algebra - and how frequently would one need do
that in PHP anyway?) operator overloading is way more trouble than it's worth and makes code
nearly unreadable as you never know what exactly each operator does. For example, if($object) would
have completely different semantics than before, for some objects but not other, and without any
obvious clue to the user what it actually does - and all that to save couple of keystrokes on
if($object->valid())?
Still, if there's a valid use case found, cast magic method and "unboxing" method may
have merit. So far the cases outlined seem either too artificial and narrow for language-level
functionality, or plain wrong (like SplFixedArray example - nothing in this proposal would enable it
to work with sort, for example). But I do not exclude other cases can exist.
However, assignment overloading does not seem viable to me.
Also, I'm not sure how this is possible technically: $obj = {expression} is supposed to replace
$obj with the result of the expression, not call methods on $obj. Doing otherwise would be huge
change in the semantics, a complete no go. Also, it's impossible if $obj is not set - meaning,
code $obj = 1 would mean totally different things depending on if $obj is set or not - again, not a
good idea. It also does not cover many corner cases but I don't even want to go there since an
idea to change semantics of the assignment seems very wrong to me in principle, so no need to go
into the fine details.
--
Stanislav Malyshev, Software Architect
SugarCRM: http://www.sugarcrm.com/
(408)454-6900 ext. 227
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