Nikolay, the has_foo being private is actually intentional, see this closed 
issue <https://github.com/google/protobuf/issues/234>.

Alfred

On Wednesday, April 29, 2015 at 6:36:59 PM UTC-4, Nikolay Mladenov wrote:
>
> I am also evaluating proto2 vs proto3 and even though it seems proto3 
> should be the way to go I really miss the has_** functionality in proto3.
>
> It seems the following proto pattern may be a workaround:
>
> message M{
>    oneof optional_value{
>      int32 value = 1;
>    }
> }
>
> It does generate value(), set_value(), clear_value() and has_value() 
> methods (C++) but unfortunately the has_value is private.
> Is there a reason such a useful and short method is declared private (it 
> implementation only uses public functionality as well)
>
>
>
> On Wednesday, February 11, 2015 at 3:55:03 PM UTC-5, Alfred Kwan wrote:
>>
>> Thanks for pointing me to "oneof". I gave it a try and I have two 
>> questions:
>> 1) I see the has_() being generated for all the fields inside oneof. Is 
>> this kind of has_() function here to stay throughout subsequent V3 releases?
>> 2) Since oneof does not allow a repeated field in both V2/3, is there 
>> pro/cons in case I create one extra layer of structure i.e.:
>> message manyMsg{ // workaround: wrap the repeating message
>>    repeated oneMsg = 1;
>> }
>> message unionMsg{
>>    oneof testOneof{
>>       manyMsg msg = 1; // doesn't allow repeated
>>       uint32 foo = 2;
>>    }
>> }
>>
>>
>>
>> On Sunday, February 8, 2015 at 11:01:04 PM UTC-5, Feng Xiao wrote:
>>>
>>> The union types are obsoleted by oneof:
>>> https://developers.google.com/protocol-buffers/docs/proto#oneof
>>>
>>> On Sat, Feb 7, 2015 at 4:53 AM, Alfred Kwan <alfr...@gmail.com> wrote:
>>>
>>>> To implement the has_boo() in 3.0 implies one boolean per each truly 
>>>> optional field, which means additional maintenance is now required, e.g. 
>>>> matching naming scheme for the pool together with the optional struct, 
>>>> also 
>>>> should we group all booleans together or should they sit right next to the 
>>>> to corresponding optional structures...
>>>>
>>>> With the uncertainty of how "any" replaces "extensions" plus the 
>>>> removal of has_boo(), it seems like new adopters (I'm one of them) should 
>>>> pick V2 over 3.0.
>>>>
>>>> On Wednesday, January 28, 2015 at 3:10:39 PM UTC-5, Feng Xiao wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Wed Jan 28 2015 at 12:06:21 PM Troy Lee <lee...@gmail.com> wrote:
>>>>>
>>>>>> Feng, 
>>>>>>
>>>>>> Version 3 removes presence logic. 
>>>>>> How do we exam whether a field is exist or not?
>>>>>>
>>>>> This is no possible for singular primitive fields. For singular 
>>>>> message fields, the has methods will still be generated. Basically with 
>>>>> proto3 you'll need to write your code without depending on these dropped 
>>>>> features. It's believed that most users don't use the field presence 
>>>>> logic 
>>>>> much and for those who need this feature adding a bool field is an easy 
>>>>> workaround.
>>>>>  
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> troylee
>>>>>>
>>>>>> Feng Xiao於 2014年12月11日星期四 UTC+8下午12時51分01秒寫道:
>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> I just published protobuf v3.0.0-alpha-1 on our github site:
>>>>>>> https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-1
>>>>>>>
>>>>>>> This is the first alpha release of protobuf v3.0.0. In protobuf 
>>>>>>> v3.0.0, we will add a new protobuf language version (aka proto3) and 
>>>>>>> support a wider range of programming languages (to name a few: ruby, 
>>>>>>> php, 
>>>>>>> node.js, objective-c). This alpha version contains C++ and Java 
>>>>>>> implementation with partial proto3 support (see below for details). In 
>>>>>>> future releases we will add support for more programming languages and 
>>>>>>> implement the full proto3 feature set. Besides proto3, this alpha 
>>>>>>> version 
>>>>>>> also includes two other new features: map fields and arena allocation. 
>>>>>>> They 
>>>>>>> are implemented for both proto3 and the old protobuf language version 
>>>>>>> (aka 
>>>>>>> proto2).
>>>>>>>
>>>>>>> We are currently working on the documentation of these new features 
>>>>>>> and when it's ready it will be updated to our protobuf developer 
>>>>>>> guide <https://developers.google.com/protocol-buffers/docs/overview>. 
>>>>>>> For the time being if you have any questions regarding proto3 or other 
>>>>>>> new 
>>>>>>> features, please post your question in the discussion group.
>>>>>>>
>>>>>>> CHANGS
>>>>>>> =======
>>>>>>> Version 3.0.0-alpha-1 (C++/Java):
>>>>>>>
>>>>>>>   General
>>>>>>>   * Introduced Protocol Buffers language version 3 (aka proto3).
>>>>>>>
>>>>>>>     When protobuf was initially opensourced it implemented Protocol 
>>>>>>> Buffers
>>>>>>>     language version 2 (aka proto2), which is why the version number
>>>>>>>     started from v2.0.0. From v3.0.0, a new language version 
>>>>>>> (proto3) is
>>>>>>>     introduced while the old version (proto2) will continue to be 
>>>>>>> supported.
>>>>>>>
>>>>>>>     The main intent of introducing proto3 is to clean up protobuf 
>>>>>>> before
>>>>>>>     pushing the language as the foundation of Google's new API 
>>>>>>> platform.
>>>>>>>     In proto3, the language is simplified, both for ease of use and 
>>>>>>>  to
>>>>>>>     make it available in a wider range of programming languages. At 
>>>>>>> the
>>>>>>>     same time a few features are added to better support common 
>>>>>>> idioms
>>>>>>>     found in APIs.
>>>>>>>
>>>>>>>     The following are the main new features in language version 3:
>>>>>>>
>>>>>>>       1. Removal of field presence logic for primitive value fields, 
>>>>>>> removal
>>>>>>>          of required fields, and removal of default values. This 
>>>>>>> makes proto3
>>>>>>>          significantly easier to implement with open struct 
>>>>>>> representations,
>>>>>>>          as in languages like Android Java, Objective C, or Go.
>>>>>>>       2. Removal of unknown fields.
>>>>>>>       3. Removal of extensions, which are instead replaced by a new 
>>>>>>> standard
>>>>>>>          type called Any.
>>>>>>>       4. Fix semantics for unknown enum values.
>>>>>>>       5. Addition of maps.
>>>>>>>       6. Addition of a small set of standard types for 
>>>>>>> representation of time,
>>>>>>>          dynamic data, etc.
>>>>>>>       7. A well-defined encoding in JSON as an alternative to binary 
>>>>>>> proto
>>>>>>>          encoding.
>>>>>>>
>>>>>>>     This release (v3.0.0-alpha-1) includes partial proto3 support 
>>>>>>> for C++ and
>>>>>>>     Java. Items 6 (well-known types) and 7 (JSON format) in the 
>>>>>>> above feature
>>>>>>>     list are not implemented.
>>>>>>>
>>>>>>>     A new notion "syntax" is introduced to specify whether a .proto 
>>>>>>> file
>>>>>>>     uses proto2 or proto3:
>>>>>>>
>>>>>>>       // foo.proto
>>>>>>>       syntax = "proto3";
>>>>>>>       message Bar {...}
>>>>>>>
>>>>>>>     If omitted, the protocol compiler will generate a warning and 
>>>>>>> "proto2" will
>>>>>>>     be used as the default. This warning will be turned into an 
>>>>>>> error in a
>>>>>>>     future release.
>>>>>>>
>>>>>>>     We recommend that new Protocol Buffers users use proto3. 
>>>>>>> However, we do not
>>>>>>>     generally recommend that existing users migrate from proto2 from 
>>>>>>> proto3 due
>>>>>>>     to API incompatibility, and we will continue to support proto2 
>>>>>>> for a long
>>>>>>>     time.
>>>>>>>
>>>>>>>   * Added support for map fields (implemented in C++/Java for both 
>>>>>>> proto2 and
>>>>>>>     proto3).
>>>>>>>
>>>>>>>     Map fields can be declared using the following syntax:
>>>>>>>
>>>>>>>       message Foo {
>>>>>>>         map<string, string> values = 1;
>>>>>>>       }
>>>>>>>
>>>>>>>     Data of a map field will be stored in memory as an unordered map 
>>>>>>> and it
>>>>>>>     can be accessed through generated accessors.
>>>>>>>
>>>>>>>   C++
>>>>>>>   * Added arena allocation support (for both proto2 and proto3).
>>>>>>>
>>>>>>>     Profiling shows memory allocation and deallocation constitutes a 
>>>>>>> significant
>>>>>>>     fraction of CPU-time spent in protobuf code and arena allocation 
>>>>>>> is a
>>>>>>>     technique introduced to reduce this cost. With arena allocation, 
>>>>>>> new
>>>>>>>     objects will be allocated from a large piece of preallocated 
>>>>>>> memory and
>>>>>>>     deallocation of these objects is almost free. Early adoption 
>>>>>>> shows 20% to
>>>>>>>     50% improvement in some Google binaries.
>>>>>>>
>>>>>>>     To enable arena support, add the following option to your .proto 
>>>>>>> file:
>>>>>>>
>>>>>>>       option cc_enable_arenas = true;
>>>>>>>
>>>>>>>     Protocol compiler will generate additional code to make the 
>>>>>>> generated
>>>>>>>     message classes work with arenas. This does not change the 
>>>>>>> existing API
>>>>>>>     of protobuf messages and does not affect wire format. Your 
>>>>>>> existing code
>>>>>>>     should continue to work after adding this option. In the future 
>>>>>>> we will
>>>>>>>     make this option enabled by default.
>>>>>>>
>>>>>>>     To actually take advantage of arena allocation, you need to use 
>>>>>>> the arena
>>>>>>>     APIs when creating messages. A quick example of using the arena 
>>>>>>> API:
>>>>>>>
>>>>>>>       {
>>>>>>>         google::protobuf::Arena arena;
>>>>>>>         // Allocate a protobuf message in the arena.
>>>>>>>         MyMessage* message = Arena::CreateMessage<MyMessage
>>>>>>> >(&arena);
>>>>>>>         // All submessages will be allocated in the same arena.
>>>>>>>         if (!message->ParseFromString(data)) {
>>>>>>>           // Deal with malformed input data.
>>>>>>>         }
>>>>>>>         // Must not delete the message here. It will be deleted 
>>>>>>> automatically
>>>>>>>         // when the arena is destroyed.
>>>>>>>       }
>>>>>>>
>>>>>>>     Currently arena does not work with map fields. Enabling arena in 
>>>>>>> a .proto
>>>>>>>     file containing map fields will result in compile errors in the 
>>>>>>> generated
>>>>>>>     code. This will be addressed in a future release.
>>>>>>> =======
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Feng
>>>>>>>
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>>>
>>>

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