On Fri, Jan 27, 2023 at 1:11 PM Alan de Freitas via Boost <boost@lists.boost.org> wrote:

Even other Asio concepts could benefit from concrete implementations in other libraries: executors, streams, tokens, etc...

Thanks... but, slow down there cowboy :) I'm only proposing buffers, and this library would not require any changes to Asio. The executor, stream, and token concepts from Asio are specific to asynchrony so I am skeptical that there is a lot of value in expressing them in their own library (and in fact I think they all need each other to be useful, i.e. an executor without an io_context is useless, as is a stream or completion token). The main purpose of Boost.Buffers is to have buffer abstractions that are independent of Asio. Thanks

Klemens Morgenstern wrote:

...

Additionally, I feel some need for a library managing raw memory. It's quite common to just use vector<unsigned char>, but I find this incorrect, because it's typed. Raw memory doesn't have a type, which is why malloc returns void* and not unsigned char*.

Raw memory bytes do have a type, and it's `unsigned char`.

Then why do malloc and operator new return void* ?

On Fri, Jan 27, 2023 at 8:09 PM Klemens Morgenstern via Boost <boost@lists.boost.org> wrote: I do like reducing dependencies, but I don't see the point of separating things just for the sake of it.

There are benefits to a strategic refactoring of composite libraries ("separating things") but that is not why I am proposing this. The answers to questions follow but before that I want to provide readers with a key insight gleaned from field experience. There is a recurring buffer motif which is a dual, that is: 1. reading from or writing into given buffers 2. providing buffers to be read from or written into These operations are fundamental, and one cannot be efficiently expressed in terms of the other. The two forms of this pattern occur with such frequency across varying domains that there is value in designing a common interface to express them. More on this later.

If you're writing a boost library most users will have installed boost as a monolith; but even those that didn't will use this in the context of http+asio so that an avoiding the inclusion of `asio/buffer.hpp` doesn't really seem like a great motivation for a new library to me.

We have libraries right now that implement serialization and parsing for things such as JSON, HTTP message bodies, deflate or gzip compression and decompression. Soon we will likely have Boost.Mustache which applies parameters to a template to produce output. And having a MIME/forms library is probably inevitable. We want to allow users to use these things as payloads for incoming or outgoing HTTP requests and responses. Currently this is done by adding the support to the library which implements the HTTP, such as Boost.Requests. Note how Boost.Requests has to know about JSON and how to serialize or deserialize it: <https://github.com/CPPAlliance/requests/blob/1214608d19f6a8c020671fcd3507e00ec6d1b3d4/include/boost/requests/json.hpp> To add support for some new body X, the structural model in use by Requests as written requires changing the Requests library itself, because the interface to serialize or parse between X and HTTP needlessly conflates networking and asio buffers as can be seen here: <https://github.com/CPPAlliance/requests/blob/1214608d19f6a8c020671fcd3507e00ec6d1b3d4/include/boost/requests/json.hpp#L98> The maintainer of Requests has to manually add a new asynchronous algorithm for every HTTP method in order to receive X as a body type. Here are the signatures for receiving a response containing body X for the HTTP methods GET, POST, and PUT. There are more methods which need to be supported but I have not bothered to link them, check the file to see them: <https://github.com/CPPAlliance/requests/blob/1214608d19f6a8c020671fcd3507e00ec6d1b3d4/include/boost/requests/json.hpp#L211> <https://github.com/CPPAlliance/requests/blob/1214608d19f6a8c020671fcd3507e00... <https://github.com/CPPAlliance/requests/blob/1214608d19f6a8c020671fcd3507e00ec6d1b3d4/include/boost/requests/json.hpp#L312> Every time Requests wants to support a new body type, it must add as a dependency the library containing the type it wishes to support. And then it must re-implement that support four times for every HTTP method: two synchronous versions (with and without exceptions) and two asynchronous versions (with and without exceptions). If Boost.Http.Proto and Beast used this model, they too would have to depend on every library which has a candidate body, and duplicate the serialization and deserialization algorithms (called BodyReader and BodyWriter in Beast). This is clearly unsustainable. I propose a better solution which eliminates almost all of the overloads by refactoring to separate concerns and allows the algorithms to be expressed once without introducing multiple dependencies. Instead of teaching Requests how to serialize and deserialize every X it wants to support, Boost.Buffers provides asio-agnostic concepts which allow the library containing X itself to provide the serialization and deserialization algorithms. Boost.JSON might add this declaration allowing a json::value to be serialized using Boost.Buffers: #include <boost/json/serializer.hpp> #include <boost/buffers/source.hpp> namespace boost { namespace json { struct json_source : buffers::source { // JSON value to serialize value const& jv; private: buffers::source::results read( buffers::mutable_buffers_pair ) override; serializer sr_; }; } // json } // boost With this in hand, Requests needs only to implement serialization of the HTTP body from a buffers::source, to be able to serialize JSON values. And it accomplishes this by adding only Boost.Buffers as a dependency, without knowing about Boost.JSON. Furthermore, every subsequent library that adds an implementation of Source for one or more of its data types will now become serializable by Requests, without Requests having to depend on that library and without that library having to depend on Requests. This works because Boost.Buffers provides a common set of vocabulary types and concepts.

I for one don't mind using sub-libraries, e.g. including boost/core for the buffer types seems ok to me.

Having asio-agnostic buffers in core is certainly better than not having them at all, but having them in their own library is better still. It gets its own library-specific documentation. It runs CI jobs faster and consumes less overall Drone resources over time. It becomes more discoverable by users. We can follow the principle of one type or concern per header file instead of cramming everything into a single buffer.hpp file. This lets downstream libraries decide which headers they actually need, to cut down on compile times. We can add useful buffer and dynamic buffer implementations such as buffers_pair, circular_buffer, flat_buffer, and the perennial favorite array_of_buffers (supporting sizes of up to one million or more). Additionally the library can be evolved independently of the Asio author which in simple terms means that open issues will receive immediate attention, emails will get answers, and the maintainers can be reached on Slack. As you said, "most users will have installed boost as a monolith." This means there is no penalty for its existence as its own Boost library. But there are the benefits stated above. These benefits are not theoretical; Requests aims to add forms, files, and various other things. When these are expressed in terms of Boost.Buffers, they will automatically work in Requests without the need to add support for it specifically. But there is another huge benefit, every library which adds support for parsing and/or serialization in terms of Boost.Buffer concepts can now be used in Boost.Http.Proto with no modification or changing of library dependencies! At this point, someone like Peter might object. He might say, well Boost.JSON doesn't care about sources and sinks it only cares about JSON. Or worse he might become dismissive if I ask him to support Boost.Buffers in the upcoming Boost.Mustache. But what is the purpose of having this giant monolith of libraries, if not to take advantage of our ability to make all the libraries work together seamlessly with the other libraries, and enhance the value of the collection as a whole?

What I would however like is a unification of the two dynamic_buffer concepts, which are currently a mess. Taking the beast buffers and making them work nicely with asio would be great.

This is a good goal, but it is orthogonal to what I am proposing here. Boost.Buffers does not use Asio, does not depend on Asio, does not require its downstream libraries to use Asio, and does not replace Asio for libraries that need to perform networking. The fact that it uses concepts that are astoundingly similar to Asio merely demonstrates that the Asio author discovered very good general purpose abstractions.

Thus a container type for a chunk of raw memory should also be included. I.e. something akin to a vector<void> if you will.

Hmm... I do not believe std::vector<void> can be made to work but we can certainly do std::vector<unsigned char> (and we should). Thanks

On Sat, Jan 28, 2023 at 7:14 AM Ruben Perez via Boost <boost@lists.boost.org> wrote:

"an owning blob view"

I believe this is just const_buffer (same in Asio and proposed Buffers) Thanks

Le 2023-01-31 07:30, Gavin Lambert via Boost a écrit :

On 28/01/2023 08:34, Vinnie Falco wrote:

...

Greetings. I am asking if there is any interest in a Boost.Buffers library, which consists of the following:

I am a little hesitant in breaking this off from Asio, since as Klemens pointed out it would be unusual to not have the header available, and since whatever is in Asio is already somewhat-standards-adjacent with some third party implementations already, making them _almost_ vocabulary types anyway. (Though of course "almost" compiles no code.)

A buffer concept has use cases outside the usual targets of asio (think of MCUs). C++/Boost currently lack a fixed size circular_buffer implementation, for example. That being said, i think we currently have a vocabulary type for non-owning non-resizable buffers: it's called span<byte>. Maybe an owning span would make some sense, to be able to transfer ownership of the underlying memory. Outside this, i'm not sure. IMHO a buffer is often just a special use case of a container. Regards, Julien

On Mon, Jan 30, 2023 at 10:31 PM Gavin Lambert via Boost <boost@lists.boost.org> wrote:

I assume also adapters from std::span<T> and ranges thereof, since those are the New Hotness?

Adapters yes but I don't know what the ranges is (probably yes to that if it makes sense).

I am a little hesitant in breaking this off from Asio, since as Klemens pointed out it would be unusual to not have the header available,

I wouldn't want Boost.JSON to depend on Boost.Asio. But I am OK with Boost.JSON depending on Boost.Buffers.

...since whatever is in Asio is already somewhat-standards-adjacent

Well the Networking TS was rejected.

(I don't know whether that makes it better or worse if your types are identical to the ASIO ones or "improved" in some way.)

I'm trying to keep things as similar as possible if for no other reason, that introducing differences can only lead to confusion. However I am fixing what I perceive to be some design flaws; wg21 has a negative impact on Asio's development. Thanks

On 3/02/2023 10:57, Andrzej Krzemienski wrote:

We have (I think a still unresolved issue) of Boost-serializing Boost.Optional. Should the code responsible for the serialization of Boost.Optional be part of Boost.Serialization or Boost.Optional? But we will certainly not solve it by introducing yet another library. There are other ways to solve it, say, through optional headers.

I think the two schools of thought on that are: 1. Serialization came first and so Optional should take it into account in its implementation. 2. Optional is more fundamental than Serialization, and you're more likely to use optionals than serialization, so the latter should have the supporting code. I personally find the second argument more compelling (although the waters are muddied by there now being a std::optional too, increasing the chance you might want serialization without caring about boost::optional), but that only solves the problem of which repository the bulk of code should belong to. Unfortunately in C++ there's no way to say "if these two otherwise unrelated headers were included then also include this", short of order-sensitive preprocessor checks. This then I think leads to only three reasonable solutions: 1. The user has to know that the integration exists and explicitly #include an additional header file (e.g. boost/serialization/optional.hpp) when they're using both together. 2. *Both* libraries need to detect the other and include the integration header from their top-level wrapper regardless of the original include order. So if the user happens to include both libraries "in general" then they get the integration automatically. 3. One library decides that the other is sufficiently "vocabulary" and/or small enough to always be loaded if the first is, and just unconditionally includes it (from the perspective of the "whole library" header, at least). For this particular case, Boost appears to have chosen #1 currently, and doesn't implement #2 or #3. These are not mutually exclusive. #2 is the most user-friendly option (#1 is less discoverable), but it's not readily extensible for detecting if std types are included, or for third-party library types unaware of Boost, making it rather awkward in practice for anything non-Boost. I'm not entirely sure how this all applies to the Buffers/Asio situation. Logically, Buffers would be more fundamental than Asio, so it would make sense for Asio to be modified to use/be compatible with Buffers (rather than the reverse, as currently seems to be proposed), though I'm not sure how well that would catch on since Asio will likely want to retain its own buffer implementations for standalone use at least.

pt., 3 lut 2023 o 02:13 Vinnie Falco via Boost <boost@lists.boost.org> napisał(a):

On Thu, Feb 2, 2023 at 2:47 PM Gavin Lambert via Boost <boost@lists.boost.org> wrote:

...

I'm not entirely sure how this all applies to the Buffers/Asio situation. Logically, Buffers would be more fundamental than Asio, so it would make sense for Asio to be modified to use/be compatible with Buffers (rather than the reverse, as currently seems to be proposed), though I'm not sure how well that would catch on since Asio will likely want to retain its own buffer implementations for standalone use at least.

Well as I mentioned in my previous message, I think that serialization is a different thing from where Buffers would be applicable. As an interesting note. Boost.JSON handles conversion of OptionalLike types to JSON when performing json::value_from and when serializing (soon). We did this not by depending on Boost.Optional but rather, defining a concept for all OptionalLike types. Generally speaking I think if a library wants to support types that match certain generic concepts, then the place for that support goes into the library itself.

On the specific topic of OptionalLike, note that we have i Boost the concept of OptionalPointee: https://github.com/boostorg/utility/blob/c960bef6ef005413d96cc7366b66cbdf56d... It is not well advertised though. It was added along Boost.Optional, but it was not clear where to put it.

I would be in favor of a Boost library which offered metafunctions for identifying types which match certain models such as OptionalLike, MapLike, StringLike (e.g convertibility to string_view), TupleLike, VariantLike and such. JSON could use that and perhaps Serialization. It might be worth exploring.

Agreed. A library for enforcing concepts from Boost.Libraries. Regards, &rzej;

I have designed Boost.Buffers to work with Asio (but without requiring Asio) to make it palatable to use. Asio changing is extremely unlikely so the burden is on Buffers to be interoperable.

On a separate note all of this talk about headers only working when other headers are "present" or anything like that, makes me uncomfortable. I like it when a build always produces one version of the library no matter what else is installed or what macros are set. I've tried to get fancy with includes and I always regretted it.

Thanks

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On 4/02/2023 07:14, Robert Ramey wrote:

...

1. The user has to know that the integration exists and explicitly #include an additional header file (e.g. boost/serialization/optional.hpp) when they're using both together.

or ... boost/optional/serialization.hpp ?

Perhaps, though as I said I find the "optional is more fundamental" argument more compelling, so by that logic the compatibility code should be in serialization and not optional. Also, boost/serialization/optional.hpp already does exist, and boost/optional/serialization.hpp does not. Though having both header files exist (with one merely a redirect to the canonical one) could be an interesting choice, to allow the user to not have to think about which one is more fundamental. (Though if one file exists and one does not, that becomes obvious fairly quickly.) One downside of the current serialization implementation is that (as far as I can see) it *only* supports boost::optional and not std::optional, and the "obvious" header name (boost/serialization/optional.hpp) is already taken. Were it to extend support for std::optional in the future, how should that look? Just detect C++17 and then assume you want it automatically? Try to auto-detect a previous #include <optional>? Assume including boost/serialization/optional.hpp means you want both? Introduce boost/serialization/std_optional.hpp? All of these choices have pros and cons. Another variant might be mixing several of these, by renaming current optional.hpp to boost_optional.hpp, adding std_optional.hpp, and then a new optional.hpp that includes one, the other, or both based on C++17 support (or detecting prior include of Boost.Optional), though there are several caveats there too.

wt., 7 lut 2023 o 00:31 Vinnie Falco via Boost <boost@lists.boost.org> napisał(a):

On Mon, Feb 6, 2023 at 2:43 PM Gavin Lambert via Boost <boost@lists.boost.org> wrote:

...

Perhaps, though as I said I find the "optional is more fundamental" argument more compelling, so by that logic the compatibility code should be in serialization and not optional.

I just want to underscore that the question of "where does optional go" is completely orthogonal to this proposed Boost.Buffers library, and the buffers::source and buffers::sink interfaces in particular. My proposed library has nothing to do with serialization and everything to do with providing buffer-oriented interfaces.

In fact, buffers::source is more fundamental than serialization. Boost.Serialization sits between buffers::source and the algorithm for serialization of an optional. This diagram shows the relationship:

{ host } <---> Boost.Buffers <---> Boost.Serialization <---> { optional }

In this diagram "host" is the host program or library which is implemented in terms of Boost.Buffer's abstract interfaces (buffers::source for the case of using Boost.Serialization). As seen in the diagram, the question of where the serialization spec for "optional" goes, is unrelated to Boost.Buffers.

Another way to think of it is like this. If Boost.Serialization implements the buffers::source interface, then any host which uses Boost.Buffers will be able to make use of types archived through Boost.Serialization. I'm not saying whether this is particularly useful or not as that would depend on the specific use-case. For the upcoming Boost.Http.Proto library, this means that anything which defines a serialization for Boost.Serialization could be attached as the body of an HTTP message.

The diagram for Boost.JSON looks different:

{ host } <---> Boost.Buffers <---> Boost.JSON

Here, if Boost.JSON wraps its existing streaming serializer for the buffers::source interface then any Boost.Buffers-enabled host can make use of JSON sources without depending on the Boost.JSON library. There's a network effect at play; every library that enables Boost.Buffers geometrically increases the utility of every other library that uses Boost.Buffers. Furthermore, this scales to any number of libraries and resolves the question of where the buffers::sink (or buffers::source) algorithm goes. It goes in the library which already implements a buffer-oriented data type. This includes but is not limited to:

* JSON * XML * Boost.Serialization archives * Mustache templates and output

As indicated earlier, I support the extraction of Boost.Buffers into a separate Boost library. Let me offer some further thoughts. 1. It is more of a question. These buffers::sink and buffers::source being mentioned in this thread: are they already present in one of the Boost libraries (ASIO, Beast)? 2. For any "vocabulary interface" we could separate out three parts: (1) the interface, (2) the sinks, (3) the sources. I am slightly abusing the terms, so let me give an example of the STL. Iterators are the interface. The algorithms are "sinks": they do not have to know about containers. The containers are the "sources" they do not have to know about iterators. If the STL was a Boost library, the only thing that other Boost libraries would depend on would be iterators -- not the algorithms, not the containers -- because it is only the iterators -- the interface -- that lets you plug your library into the system. I see the same situation with the proposed Boost.Buffers. The only thing that multiple libraries (Boost and non-Boost) would benefit from is the buffer interface (boost::sink, boost::source). No buffer implementations, no buffer algorithms. As you mentioned earlier, things like a circular buffer are shared between at least two libraries, so there is a merit in separating this, but this is just an engineering trade-off, rather than a vocabulary interface design (like boost::sink, boost::source). This remark applies to every library with a sound vocabulary-like interface: the interface should go separately. But that would be a very small library, maybe not worth a separate infrastructure. 3. There are a number of interfaces, where everyone can plug their type, in the STD and Boost that have an overlap. We have the IOStream interface, we have Boost.Serialization interface, std::format is coming, and we have now Boost.Buffer being proposed. Can you make a clear distinction why Boost.Buffers is different? Why do we need another one? Are previous ones defective (and can be superseded), or do they play a different, incompatible role? I suppose that buffers have much to do with buffering, that is working with chunks of messages. But how does this work with JSON? Can you even start thinking about parsing JSON if you only have a part, broken at an arbitrary position? Also, IOStreams have a layer of buffers. What is the relation there (Between IOStream buffers and the proposed Boost.Buffers)? 4. Would Boost.Buffers satisfy my every use case for buffers? Are buffers only about how you allocate a new chunk of memory? Or are they about identifing a place where you can cut your message into meaningful portions? Regards, &rzej;

On 2/6/23 2:43 PM, Gavin Lambert via Boost wrote:

On 4/02/2023 07:14, Robert Ramey wrote:

...

...

1. The user has to know that the integration exists and explicitly #include an additional header file (e.g. boost/serialization/optional.hpp) when they're using both together.

or ... boost/optional/serialization.hpp ?

I think we're off-topic - but what the hell.

Perhaps, though as I said I find the "optional is more fundamental" argument more compelling, so by that logic the compatibility code should be in serialization and not optional.

My rule has always been: if it's in the standard library, put it in boost/serialization/... otherwise, put it in boost/<library name>/serialization.hpp I didn't see any natural place for the standard library serializations so I put them boost/serialization. A big problem is that a number of library maintainers object to putting the serialization code for their data types into their libraries and won't do it. This explains the "optional" anomaly you've noted. They don't like it because our "dependency checking tools" Will show a dependency on serialization if the serialization library is referred to anywhere in a library, even if only in tests! Basically "dependency" would depend on whether an application actually serializes that type. Of course if one is building a shared library it's different - everything has to be included. Sorry for the wordy explanation, but I didn't have time to make it shorter.

Also, boost/serialization/optional.hpp already does exist, and boost/optional/serialization.hpp does not.

Because the maintainer of optional has chosen not to. If I put it in serialization, I'm signing on to adding/maintaining serialization types in all libraries. Probably not a wise idea. I don't want the work and I'm 75 years old.

Though having both header files exist (with one merely a redirect to the canonical one) could be an interesting choice, to allow the user to not have to think about which one is more fundamental.  (Though if one file exists and one does not, that becomes obvious fairly quickly.)

So it's not a question of which is more "fundamental", which would always be subjective, it's just the simple rule above.

One downside of the current serialization implementation is that (as far as I can see) it *only* supports boost::optional and not std::optional, and the "obvious" header name (boost/serialization/optional.hpp) is already taken.  Were it to extend support for std::optional in the future, how should that look?  Just detect C++17 and then assume you want it automatically?  Try to auto-detect a previous #include <optional>?  Assume including boost/serialization/optional.hpp means you want both?  Introduce boost/serialization/std_optional.hpp?  All of these choices have pros and cons.

I think there is an implementation of serialization posted as a PR.

Another variant might be mixing several of these, by renaming current optional.hpp to boost_optional.hpp, adding std_optional.hpp, and then a new optional.hpp that includes one, the other, or both based on C++17 support (or detecting prior include of Boost.Optional), though there are several caveats there too.

This really is a question regarding "bridge libraries" which have a foot in more than library. The "real" solution would be a separate "library" which would contain just the serialization implementations for all types.

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On Thu, Feb 2, 2023 at 1:58 PM Andrzej Krzemienski <akrzemi1@gmail.com> wrote:

Today the basics for networking seems like good candidates for vocabulary types. Is Boost.Buffer a candidate for such a vocabulary type?

In theory, yes. The intent is for Buffers to be more general than just networking.

First question, is this library to be consumed directly by user programs, or only by other libraries, such as Boost.Beast and Boost.Http.Proto?

User programs could use it when they want to express algorithms in terms of ranges of buffers. My personal use-case is Beast, HTTP, Websocket, and JSON but this could be extended to say, base64 encoding and decoding, calculating SHA-2 digest over a range of buffers, simplified front end to things like zlib. Example: template< class DynamicBufferOut, class DynamicBufferIn > result< void > deflate( z_params&, DynamicBufferOut& DynamicBufferIn&, bool end_of_data);

Is it possible that the final program that uses Boost.Buffer will not use Boost.ASIO?

That is possible, yes.

For me, as a consumer of networking libraries, who can afford to download and build the entire set of Boost libraries, the biggest advantage would be that Buffers would be well documented and tested.

That is an advantage yes but in my opinion the advantage is that you get access to a rich and useful set of algorithms, containers, and concepts, without also depending on a particular network implementation.

I am not convinced by the argument with Boost.JSON not depending on ASIO.

Well, users definitely do not want to drag in Asio with their JSON.

We have (I think a still unresolved issue) of Boost-serializing Boost.Optional. Should the code responsible for the serialization of Boost.Optional be part of Boost.Serialization or Boost.Optional? But we will certainly not solve it by introducing yet another library.

I think that the cases of Boost.Serialize with boost::optional, and serialization of JSON using Boost.JSON and Boost.Buffers are two completely different cases. Boost.Serialize does not define a serialization format but rather a framework for allowing the user to define serialization. Boost.JSON is something else entirely; it is a library which implements a specific protocol for describing data using structured text. If you look at Boost.JSON you see that it has json::parser and json::serializer. These classes work a buffer at a time and they support streaming; that is, that the entire input or output need not be presented at once in order to make progress. How does Boost.Buffers help here? Well.. it provides the means for a library such as JSON, which has algorithms to produce or consume a buffer at a time, to type-erase its algorithm using the buffers::source or buffers::sink interfaces: /// An algorithm which consumes filled buffers struct sink { virtual ~sink() = 0; /** Called when data is available */ virtual result<void> write( span< const_buffer const > ) = 0; }; /// An algorithm which produces filled buffers struct source { /** The results of reading from the source. */ struct results { error_code ec; std::size_t bytes = 0; bool more = false; }; virtual ~source() = 0; /** Called when more data is required This function is invoked when more data is required. The subclass should place zero or more bytes into the buffers referenced by `dest`, and return a `results` value with the members set appropriately. <br> Partial success is possible. */ virtual results read( span< mutable_buffer const > dest ) = 0; }; This is not really any different from libraries that support operator<<(std::ostream&), except that the vocabulary type is buffers::sink and buffers::source instead of std::istream and std::ostream. When Boost.JSON implements these APIs, it is not "supporting Boost.Serialization" it is merely providing a wrapper for the algorithms it already has (json::parser and json::serializer) to adapt them to a common, agreed-upon interface (the buffers::sink and the buffers::source). Currently users complain that Boost is a huge bundle of libraries, and at some level this is true. But it is a bundle of libraries for a reason, because releasing the collection together as a unit allows us to ensure that all the components work together. But more importantly it allows a member library to leverage the advantages of having other member libraries available to it (Config, Variant2, mp11 come to mind). The point of implementing Boost.Buffers' sink and source interfaces in JSON is to let us leverage the benefits of the monolithic distribution model.

Boost.JSON doesn't need to depend on the implementation of the circular buffer.

Right, it wouldn't. It would only be implementing the sink and source abstract interfaces. This let's JSON participate in the growing ecosystem of Boost.Buffers enabled algorithms. I think JSON is the place for it, because the model can scale. Candidate libraries which would add value by implementing source and sink do so in the library itself. The model where a single library has to depend on an ever increasing number of other libraries in order to implement their wrappers is unsustainable. -- Regards, Vinnie Follow me on GitHub: https://github.com/vinniefalco

On 2/2/23 1:57 PM, Andrzej Krzemienski via Boost wrote:

Should the code responsible for the serialization of Boost.Optional be part of Boost.Serialization or Boost.Optional? But we will certainly not solve it by introducing yet another library. There are other ways to solve it, say, through optional headers.

This question comes up all the time and had never been been "solved" to everyone's satisfaction.

Regards, &rzej;

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