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Date: Mon, 6 May 2013 12:44:19 -0400
Message-ID: <CADqTB_jqHCLKNMbCbpYrnJJJZNkW0YgZ1iJWqMf30qgPCZAHUg@mail.gmail.com>
To: Seva Lapsha <seva.lapsha@gmail.com>
Cc: Stas Malyshev <smalyshev@sugarcrm.com>, PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=20cf3079b5dc81463804dc0f6923
Subject: Re: [PHP-DEV] property de-referencing
From: rasmus@mindplay.dk (Rasmus Schultz)

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Seva,

I understand that you can reference properties more consistently
using "{fullClassName}::{fieldName}" notation, but it's still a string, and
although it's now almost practically safe to assume that strings formatted
in that way are property-references, it still doesn't address the problem
in a way that is elegant or expressive.

I don't think the Symfony component could have done a much better job under
the circumstances, at least not without the sacrifice of readable code -
typing out new PropertyReference($object, 'User::$name') sure would be
clunky, and not even really safe, since you can't guarantee that the
class-name of $object is known, and in every property-reference, the User
class-reference is now embedded statically in every property-reference, in
the form of a string.

I think this is a good example of those times when PHP developers tend to
look far, far away from Java - as far away as possible - for solutions that
are elegant and a good fit for PHP.

new PropertyReference($object, 'User::$name') contains two static
references too many, to both PropertyReference and User.

As opposed to ^$user->name which contains the minimum amount of required
information - the object and property-name, nothing else.


On Mon, May 6, 2013 at 12:08 PM, Seva Lapsha <seva.lapsha@gmail.com> wrote:

> Hi Rasmus,
>
> I agree with you that strings are not the best way to refer to an element
> sometimes. However, to me your Symfony2 example only demonstrates the flaw
> of the component's design decision, not the limitation of the language.
> Sometimes developers (not just Symfony, but other frameworks too) don't
> hesitate to use contextless strings to refer to meta-data, because they
> underestimate the importance of keeping static referability of static
> entities. If they would use conventional full notation of references, e.g.
> "{fullClassName}::{fieldName}" in a string, this would solve your initial
> problem (and allow static analyzers which could be aware of the context of
> the framework to do their job). This is how these kind of dilemmas are
> solved in the world of Java for instance, where property references don't
> exist too.
>
> Regards,
> Seva
>
>
> On Tue, Apr 30, 2013 at 6:24 PM, Rasmus Schultz <rasmus@mindplay.dk>wrote:
>
>> Any PHP dev who works with a mainstream framework does this daily, but the
>> frameworks rely on strings for property-names.
>>
>> Take this example from the Symfony manual, for example:
>>
>>
>>         class Task
>>         {
>>             protected $task;
>>
>>             protected $dueDate;
>>
>>             public function getTask()
>>             {
>>                 return $this->task;
>>             }
>>             public function setTask($task)
>>             {
>>                 $this->task = $task;
>>             }
>>
>>             public function getDueDate()
>>             {
>>                 return $this->dueDate;
>>             }
>>             public function setDueDate(\DateTime $dueDate = null)
>>             {
>>                 $this->dueDate = $dueDate;
>>             }
>>         }
>>
>>         $form = $this->createFormBuilder($task)
>>             ->add('task', 'text')
>>             ->add('dueDate', 'date')
>>             ->getForm();
>>
>> In this example, 'task' and 'dueDate' are property-references - except of
>> course that, no, they're not - they're obviously just strings... rewriting
>> this example to use a (fictive) form builder API with static
>> property-references:
>>
>>         $form = $this->createFormBuilder()
>>             ->add(^$task->task, 'text')
>>             ->add(^$task->dueDate, 'date')
>>             ->getForm();
>>
>> We now have static property-references, which means the codebase can be
>> proofed using static analysis, which also means better IDE support with
>> property auto-completion, inline documentation, and automatic refactoring
>> for operations like renaming properties, etc.
>>
>> Note that $task need not be passed to createFormBuilder() anymore -
>> instead, we can now use PropertyReference::getObject() inside the
>> form-builder to obtain the instance.
>>
>> For that matter, we can now scrap the form-builder entirely and introduce
>> a
>> simple form-helper in the view instead:
>>
>>     Task name: <?= $form->textInput(^$task->task) ?>
>>     Due Date: <?= $form->dateInput(^$task->dueDate) ?>
>>
>> This is even better, because we now have the same level of IDE support and
>> static analysis for textInput() and dateInput() which were previously
>> unchecked strings.
>>
>> Or even simpler:
>>
>>     Task name: <?= $form->input(^$task->task) ?>
>>     Due Date: <?= $form->input(^$task->dueDate) ?>
>>
>> Using PropertyReference::getObject() and reflection inside the
>> form-helper's input() method, we can now use property-annotations to
>> specify the input-type. This is a matter of preference of course, but use
>> of annotations in Symfony is pretty popular.
>>
>> This is just one example - most PHP devs (at least those who do PHP for a
>> living) use form abstractions and object/relational-mappers of some sort,
>> so this has practical applications for practically everyone, everywhere.
>>
>> Rasmus Lerdorf wrote:
>>
>> It is certainly not worth overloading the XOR operator for
>>
>>
>> Are we really going to quibble about syntax? This adds nothing to this
>> discussion. And as I explained earlier, the ^ operator is used for the
>> sake
>> of discussion only - if it's more practical to use another character for
>> this operator, I don't care what it looks like.
>>
>>
>> On Tue, Apr 30, 2013 at 4:58 PM, Stas Malyshev <smalyshev@sugarcrm.com
>> >wrote:
>>
>> > Hi!
>> >
>> > > I'm proposing we need a way to statically reference an object
>> property -
>> > > the object property itself, not it's value:
>> >
>> > You probably have use case for that, and it should be pretty easy to
>> > write a class that does that, but why it should be in the language? It
>> > certainly doesn't look like something sizeable portion of PHP devs would
>> > do frequently.
>> >
>> > --
>> > Stanislav Malyshev, Software Architect
>> > SugarCRM: http://www.sugarcrm.com/
>> > (408)454-6900 ext. 227
>> >
>>
>
>

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