From shade at openjdk.java.net  Thu Nov 11 00:00:01 2021
From: shade at openjdk.java.net (Aleksey Shipilev)
Date: Thu, 11 Nov 2021 00:00:01 GMT
Subject: RFR: make FieldLayout#data() public
In-Reply-To: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
References: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
Message-ID: <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>

On Tue, 9 Nov 2021 17:25:17 GMT, Ivan Ponomarev <duke at openjdk.java.net> wrote:

> Can we have this property public? This is needed for https://github.com/atp-mipt/ljv visualizer: we can use JOL to get object fields in consistent order, but then we also need `FieldData` itself in order to get fields' values

I want to keep the API as narrow as possible, I am sure you understand.
Do you need `data()` accessor now? Do you need `refField()` accessor?
Can you pseudo-code or point the usage example?

Maybe it would be better to provide the specific accessor, like: 

Object value(Object instance) { 
  if (instance == null) {
     return null;
  }
  return ObjectUtils.value(instance, f);
}


Also, LJV seems to overlap with JOL quite significantly, so maybe it would be even better to merge LJV into JOL, so that it can get whatever JOL internals it needs ;)

-------------

PR: https://git.openjdk.java.net/jol/pull/19

From duke at openjdk.java.net  Thu Nov 11 00:00:02 2021
From: duke at openjdk.java.net (Ivan Ponomarev)
Date: Thu, 11 Nov 2021 00:00:02 GMT
Subject: RFR: make FieldLayout#data() public
In-Reply-To: <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>
References: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
 <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>
 <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>
Message-ID: <yF-MG2jBqoPp0qb99xX0BjFTrLgrSfQfbaWf5Gw8xNA=.06cbdd1d-aec1-46d6-b9a8-fe7ef523433f@github.com>

On Tue, 9 Nov 2021 17:51:17 GMT, Ivan Ponomarev <duke at openjdk.java.net> wrote:

> Maybe it would be better to provide the specific accessor

Added accessors for field's value and the `Field` itself. The reason why `value` alone is not enough: we want exact field's type information.

-------------

PR: https://git.openjdk.java.net/jol/pull/19

From duke at openjdk.java.net  Thu Nov 11 00:00:00 2021
From: duke at openjdk.java.net (Ivan Ponomarev)
Date: Thu, 11 Nov 2021 00:00:00 GMT
Subject: RFR: make FieldLayout#data() public
Message-ID: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>

Can we have this property public? This is needed for https://github.com/atp-mipt/ljv visualizer: we can use JOL to get object fields in consistent order, but then we also need `FieldData` itself in order to get fields' values

-------------

Commit messages:
 - add specific accessors for field and field value
 - make FieldLayout#data() public

Changes: https://git.openjdk.java.net/jol/pull/19/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jol&pr=19&range=00
  Stats: 27 lines in 1 file changed: 27 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jol/pull/19.diff
  Fetch: git fetch https://git.openjdk.java.net/jol pull/19/head:pull/19

PR: https://git.openjdk.java.net/jol/pull/19

From duke at openjdk.java.net  Thu Nov 11 00:00:01 2021
From: duke at openjdk.java.net (Ivan Ponomarev)
Date: Thu, 11 Nov 2021 00:00:01 GMT
Subject: RFR: make FieldLayout#data() public
In-Reply-To: <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>
References: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
 <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>
Message-ID: <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>

On Tue, 9 Nov 2021 17:33:59 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Maybe it would be better to provide the specific accessor, like:

You mean the accessor for `FieldData` class? Yeah it would be nice, but it will not be sufficient for us to have it on `FieldLayout` level (we need field's type `Class` etc.)

> maybe it would be even better to merge LJV into JOL

Well, definitely yes at some point... I use LJV as a playground for my students to teach them Java programming / opensource contributing and the project is being rewritten at the moment. When it stabilizes, I will try to merge it

> Can you pseudo-code or point the usage example?


for (FieldLayout fieldLayout : ClassLayout.parseClass(obj.getClass()).fields()) {
            Field f = fieldLayout.data().refField();

            Object v = ObjectUtils.value(obj, f); //primitives are wrapped, type information lost!

            //We need everything that can be extracted from Field...
            refField.getAnnotations()... //e.g. paint the field a specific color
            refField.getGenericType()... //e.g. label the field with type information

            if (refField.getType() is primitive or can be treated as primitive per LJV setup){
                //treat the value as primitive...

            } else {
                //walk further the object's graph...
            }
        }

-------------

PR: https://git.openjdk.java.net/jol/pull/19

From shade at openjdk.java.net  Thu Nov 11 00:00:03 2021
From: shade at openjdk.java.net (Aleksey Shipilev)
Date: Thu, 11 Nov 2021 00:00:03 GMT
Subject: RFR: make FieldLayout#data() public
In-Reply-To: <yF-MG2jBqoPp0qb99xX0BjFTrLgrSfQfbaWf5Gw8xNA=.06cbdd1d-aec1-46d6-b9a8-fe7ef523433f@github.com>
References: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
 <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>
 <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>
 <yF-MG2jBqoPp0qb99xX0BjFTrLgrSfQfbaWf5Gw8xNA=.06cbdd1d-aec1-46d6-b9a8-fe7ef523433f@github.com>
Message-ID: <KzQ_z5z5qheCvxSbnlXAISXM78hButfgikB2ridv0a8=.b6357de5-a313-4500-823e-8f6a4ab52c12@github.com>

On Wed, 10 Nov 2021 08:04:41 GMT, Ivan Ponomarev <duke at openjdk.java.net> wrote:

> > Maybe it would be better to provide the specific accessor
> 
> Added accessors for field's value and the `Field` itself. The reason why `value` alone is not enough: we want exact field's type information.

There is already `typeClass()`. Do you actually need `Class<?>` out of it? I am not sure that one is always accessible.

-------------

PR: https://git.openjdk.java.net/jol/pull/19

From shade at openjdk.java.net  Fri Nov 19 12:01:57 2021
From: shade at openjdk.java.net (Aleksey Shipilev)
Date: Fri, 19 Nov 2021 12:01:57 GMT
Subject: RFR: make FieldLayout#data() public
In-Reply-To: <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>
References: <x9SW-1h4n52VARb4HT1KbgdJshfaDFR0ceVncLMSXe0=.9bb43b7f-d377-4423-97a2-643949013bdd@github.com>
 <fWPANuTF8_NBUSHOx4_nT6DHmSZ8nwinqlJ02IOCUr4=.5f8d539a-8bf1-463c-97a3-01f2531b6f0e@github.com>
 <Y49c2Z2kMUq_KMz1cK7b2qPsAU_FFO-r9xRV34BlvZ0=.8c483a0e-ab9f-436d-9ad5-559be723ad1f@github.com>
Message-ID: <leGFCaW5Ma5eObzSlYDcKQMZvzHaSurPgKdImUI67hg=.d821d1f8-2038-4ba0-bd7d-f176c43d90c0@github.com>

On Wed, 10 Nov 2021 08:26:28 GMT, Ivan Ponomarev <duke at openjdk.java.net> wrote:

> > Can you pseudo-code or point the usage example?
> 
> ```
> for (FieldLayout fieldLayout : ClassLayout.parseClass(obj.getClass()).fields()) {
>             Field f = fieldLayout.data().refField();
> 
>             Object v = ObjectUtils.value(obj, f); //primitives are wrapped, type information lost!
> 
>             //We need everything that can be extracted from Field...
>             refField.getAnnotations()... //e.g. paint the field a specific color
>             refField.getGenericType()... //e.g. label the field with type information
> 
>             if (refField.getType() is primitive or can be treated as primitive per LJV setup){
>                 //treat the value as primitive...
> 
>             } else {
>                 //walk further the object's graph...
>             }
>         }
> ```

It looks to me that this code tries to do the iteration that `GraphLayout.parseInstance` already does. Maybe you just want to extend `GraphWalker` to get this walk?

-------------

PR: https://git.openjdk.java.net/jol/pull/19