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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: Allowing property getters without a "get" prefix on DataObjects
Date Tue, 25 Sep 2018 14:23:32 GMT
> "Should Cayenne by default work without prefixed accessors".

My answer to this : "By default, no. As a fallback or a custom strategy, possibly."

I actually agree about Java beans. They are almost irrelevant now. And I wish Java gets "data
classes" and some transparent form of "properties". 

As things stand now though, there's no common established alternative based on a naming convention
that we can safely hardcode without causing grief for someone because they didn't expect that
their method would be called when evaluating expressions. Hence my preference for a DI fix.

So how about this... Unless someone else steps in by then, let me brainstorm it with Nikita
a couple of weeks from now and see if we can do a DI solution. It is not nearly as involved
as it appears.

Andrus


> On Sep 25, 2018, at 9:59 AM, Hugi Thordarson <hugi@karlmenn.is> wrote:
> 
> Hi Andrus and thanks for the reply,
> 
> allowing replacement of the entire reflection strategy is certainly nice and would allow
me to make the customizations I need.
> 
> However, if it's OK with you, rather than discuss implementation details, I'd like to
take two steps back and revert to the more philosophical design question of:
> 
> "Should Cayenne by default work without prefixed accessors".
> 
> What is there to be lost or gained from keeping or abandoning the prefix-requirement?
> 
> I believe I can safely assert that Cayenne works fine without accessor prefixes, since
I've used it that way on dozens of projects, so it looks like a somewhat arbitrary limitation.
It's only with the introduction of field based DOs that we get a problem in a very isolated
part of the framework.
> 
> It seems to me that the java ecosystem is moving towards more modern API design—we've
even got the architect of the Java language calling the bean-style "at best a questionable
-- and certainly overused -- API naming convention" [http://cr.openjdk.java.net/~briangoetz/amber/datum.html
<http://cr.openjdk.java.net/~briangoetz/amber/datum.html>] (pardon the appeal to authority,
but considering where it comes from, it's probably a good barometer for where java language
and API design is headed).
> 
> I'd say that the framework would be well served and future-proofed by dropping the requirement
for hard-coded accessor prefixes as a baked in requirement.
> 
> Cheers,
> - hugi
> 
> 
> 
>> On 25 Sep 2018, at 11:15, Andrus Adamchik <andrus@objectstyle.org> wrote:
>> 
>> Hi Hugi,
>> 
>> My vote would be to do it right. There is a positive side effect that the entire
reflection strategy suddenly becomes customizable.
>> 
>> Andrus
>> 
>> 
>>> On Sep 25, 2018, at 7:11 AM, Hugi Thordarson <hugi@karlmenn.is> wrote:
>>> 
>>> Hi Andrus, and y'all.
>>> 
>>> I've been looking into this and it seems like a rather large change to allow
something relatively simple (allowing DataObjects to have accessor methods that don't start
with a "get"-prefix).
>>> 
>>> Would people be diametrically opposed to just changing BeanAccessor so that it
seeks for a non-prefixed method if a prefixed one isn't found? That modification is minimal
and shouldn't affect any current users, so I can think of.
>>> 
>>> Cheers,
>>> - hugi
>>> 
>>> 
>>> 
>>>> On 20 Sep 2018, at 16:08, Andrus Adamchik <andrus@objectstyle.org>
wrote:
>>>> 
>>>> Hi Maik,
>>>> 
>>>> In Cayenne a canonical way to override services is via DI. A PR that follows
that approach has a good chance of acceptance. 
>>>> 
>>>> From a quick glance, I wonder if this new DI endpoint should be a factory
of ClassDescriptorMap (which is currently lazily created inside EntityResolver). We can't
make ClassDescriptorMap itself DI-managed as it depends on the mapping state, but a factory
for it can be a DI singleton. Inside your custom factory (a few levels down actually) you
can provide a subclass of BeanAccessor (maybe also via its own DI factory?).
>>>> 
>>>> Andrus
>>>> 
>>>> 
>>>>> On Sep 19, 2018, at 8:35 AM, Maik Musall <maik@selbstdenker.ag>
wrote:
>>>>> 
>>>>> Hi all,
>>>>> 
>>>>> I'd like to pull up this discussion from one year ago again. I'm currently
running 4.0 and testing upgrading to 4.1 using field-based DataObjects, and I'm hitting the
hard-coded prefixes in BeanAccessor that prevent me from proceeding.
>>>>> 
>>>>> Yes, in theory I could sigh, yield, and use "get" prefixes, but not only
do I dislike introducing the "get" boilerplate everywhere. I am also somewhat reluctant to
make a refactoring touching some 800+ files in my project. To be honest, I'd rather patch
BeanAccessor to personal taste and deal with the consequences.
>>>>> 
>>>>> BeanAccessor is currently always called by it's constructor. In addition
to the options Hugi described in his original mail in this thread, I could also imagine a
way to modify this to be able to inject a custom Accessor implementation as an alternative.
What do you think?
>>>>> 
>>>>> And… what would happen if someone would submit a pull request actually
implementing one of these options? :-)
>>>>> 
>>>>> Cheers
>>>>> Maik
>>>>> 
>>>>> 
>>>>>> Am 26.09.2017 um 15:32 schrieb Hugi Thordarson <hugi@karlmenn.is>:
>>>>>> 
>>>>>> Hi Michael,
>>>>>> 
>>>>>> thanks for an honest attempt to convince me. Hard sell, though. :)
>>>>>> 
>>>>>> I use a lot of 3rd party libraries and I've only hit one time where
using the bean spec was necessary — JasperReports. That was easily fixed by providing *BeanInfo
classes, in accordance with the Bean spec. But Cayenne doesn't really follow the Java Bean
Spec, it just hardcodes "is", "get" and "set".
>>>>>> 
>>>>>> As for the Eclipse thing… Well. A standard DataObject already has
five methods prefixed with "get" so that list is questionable. And I don't miss this functionality.
>>>>>> 
>>>>>> I think it's important to note that the change I'm proposing would
not affect those who choose to add the prefix. It just accommodates those of us who choose
not to, thus expanding the audience of the framework.
>>>>>> 
>>>>>> Cheers,
>>>>>> - hugi
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> On 26 Sep 2017, at 12:01, Michael Gentry <blacknext@gmail.com>
wrote:
>>>>>>> 
>>>>>>> Hi Hugi,
>>>>>>> 
>>>>>>> Let me try to sell you on the "get" prefix.  :-)
>>>>>>> 
>>>>>>> (I did a lot of WebObjects/EOF in the past, in Objective-C and
Java, so I
>>>>>>> understand the reluctance.)
>>>>>>> 
>>>>>>> * The "get" prefix is part of the JavaBeans standard/contract.
 With the
>>>>>>> exception of "is" for booleans (with a little "b").
>>>>>>> 
>>>>>>> * There are tons of Java frameworks out there that expect and
utilize the
>>>>>>> JavaBeans contract, so it is great for folding external frameworks
into
>>>>>>> your code.  Or folding Cayenne into other frameworks, such as
Tapestry.  I
>>>>>>> can specify Cayenne object/relationship paths in Tapestry (and
other
>>>>>>> frameworks) such as
>>>>>>> t:value="currentItem.resourceSummary.grossCost.costs.continuingFootnote"
>>>>>>> (real example).  Since Tapestry expects the JavaBeans contract
and Cayenne
>>>>>>> provides it, this works flawlessly.
>>>>>>> 
>>>>>>> * In Eclipse (and others, I'm sure) I can do anObject.get[pause
or
>>>>>>> control-space] and see all the getters associated with that object.
>>>>>>> Without the get prefix, they are spread out a-z and therefore
you can't get
>>>>>>> as concise a list.
>>>>>>> 
>>>>>>> mrg
>>>>>>> 
>>>>>>> 
>>>>>>> On Tue, Sep 26, 2017 at 7:02 AM, Hugi Thordarson <hugi@karlmenn.is>
wrote:
>>>>>>> 
>>>>>>>> Hi all
>>>>>>>> 
>>>>>>>> Touching on an old subject that has now become more important
with
>>>>>>>> field-based Data Objects.
>>>>>>>> 
>>>>>>>> All of my DataObjects use accessor methods without the "get"-prefix.
This
>>>>>>>> was fine with Map Based data objects (where a MapAccessor
would get
>>>>>>>> property values by name), but now that my objects are field
based, along
>>>>>>>> comes BeanAccessor which is hardcoded to have every getter
prefixed.
>>>>>>>> 
>>>>>>>> I propose that BeanAccessor be modified to allow accessor
methods without
>>>>>>>> the "get"-prefix. Methods with "get" would get precedence,
but if no method
>>>>>>>> with a "get"-prefix exists, check for the existence of a
method with only
>>>>>>>> the property name.
>>>>>>>> 
>>>>>>>> Although it's a minimal change in code, I realise it comes
with a bit of
>>>>>>>> potential baggage WRT testing. But this is not just to scratch
a personal
>>>>>>>> itch; once Cayenne 4.0 is out I want to start a large scale
introduction of
>>>>>>>> Cayenne to the EOF world where the get prefix is generally
not liked and
>>>>>>>> this change would have a big appeal. Besides, I'm not a big
fan of the
>>>>>>>> get-prefix myself, I find it a bit redundant :).
>>>>>>>> 
>>>>>>>> An alternative would be to adhere to the Bean standard, and
make
>>>>>>>> BeanAccessor read bean meta information (usually specified
in *BeanInfo
>>>>>>>> classes) and get names of getter/setter methods from there.
But that would
>>>>>>>> be a much larger change than just checking for a method with
propertyName
>>>>>>>> if the getPropertyName method doesn't exist.
>>>>>>>> 
>>>>>>>> What do you think?
>>>>>>>> 
>>>>>>>> Cheers,
>>>>>>>> - hugi
>>>>>> 
>>>>> 
>>>> 
>>> 
>> 
> 


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