[TYPO3-50-general] Improvment for Injections?!?

[Robert Lemke]

Hi Malte,

I changed my mind (a bit): FLOW3 now supports Property Injection - not  
with
public but with protected properties!

See http://flow3.typo3.org/documentation/reference/object/

Cheers,
robert

Am 12.01.2009 um 09:38 schrieb Malte Jansen:

> Hi Robert,
>
> ok
> it just came into my minde...
> Perhaps DEV3 could add some autocompletion for injections, so you  
> don't
> have to write so much simluar code.
>
> Cheers,
>
> Malte
>
> Robert Lemke schrieb:
>> Hi Malte,
>>
>> Am 11.01.2009 um 19:46 schrieb Malte Jansen:
>>
>>> it would be nice get some feedback...
>>> Bad idea? Not possible? Perhaps later? We working on it ;) ?
>>
>> sorry, forgot about this thread.
>>
>>> Malte Jansen schrieb:
>>>> Hi,
>>>>
>>>> I just tested the AOP and discovered, if you just use an aspect for
>>>> injecting a class.
>>>>
>>>> So what about some injecting the Classes via a DocComment-Tag- 
>>>> Syntax?
>>>> e.g.
>>>> @inject $objectFactory F3::FLOW3::Object::FactoryInterface
>>>> @inject property F3::MyPackage::MyClassInterface
>>>>
>>>> There is no autocompleting, but the outline of a class has less  
>>>> entries
>>>> and injecting something is more or less more an AOP-aspect, than
>>>> belonging to a model.
>>>>
>>>> And if you want to test a class, you can use the old-fashioned- 
>>>> syntax
>>>> (implemented somehow as aspect):
>>>> public function  
>>>> injectObjectFactory(F3::FLOW3::Object::FactoryInterface
>>>> $objectFactory);
>>>>
>>
>>
>> Although it sounds tempting, there are a few issues with this  
>> solution:
>>
>> 1. Readibility / Black Magic
>>
>>    All code a class uses internally should actually be found in the  
>> class
>>    itself (or one of the parent classes). It would be too much  
>> magic if
>>    the class code referred to $this->objectFactory but there is no  
>> such
>>    property defined and no method which fills that property.
>>
>>    Cross-cutting concerns, which are extracted by AOP, are a  
>> different
>> thing:
>>    Although they introduce new functionality, the target class does  
>> not
>> refer
>>    to it - it doesn't even know about it.
>>
>>    Although it could be argued that annotations are well enough
>> readable for
>>    this mechanism, injection of dependencies is simply not a cross- 
>> cutting
>>    concern but an important part of the class construction.
>>
>> 2. Loss of contract
>>
>>    No matter if your class implements an interface or not, third  
>> party
>> code
>>    will rely on the set of public functions your class provides. If  
>> this
>>    code wants to call an inject method (or a regular setter), it  
>> doesn't
>>    know for sure if it exists.
>>
>> 3. Testing
>>
>>    Most importantly, tests should always work without the AOP
>> framework, because
>>    only this guarantees that you're testing the code you want (and  
>> not
>> the woven-in
>>    functionality). You write:
>>
>>>> And if you want to test a class, you can use the old-fashioned- 
>>>> syntax
>>
>>    You always want to test a class of course, therefore you always
>> would have to
>>    use the old-fashioned syntax.
>>
>> The basic idea you had is not wrong though, it surely would be nice  
>> to
>> simplify
>> setter injection. A cleaner but still not clean approach would be to
>> declare
>> public properties which are then automatically filled from outside:
>>
>>   /**
>>    * @var F3\FLOW3\Object\Factory\Interface
>>    */
>>   public $objectFactory;
>>
>> But I never really liked that solution because it conflicts with our
>> rule of not
>> having public properties at all.
>>
>> So, I'd say, for the time being it's nothing I'd like to see  
>> support for
>> in FLOW3.
>>
>> Cheers,
>> robert
>
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