Add support for constructing Buffer from std::array

[tgaldes]

No description provided.

[mfontanini]

Thanks for the PR! Minor comment.

[mfontanini]

Minor: can you use data.data() and data.size() rather than &data[0] and N * sizeof(T) here?

[tgaldes]

will do! first time working with std::arrays

[mfontanini]

Perfect, that works! One more thing: can you add a deleted constructor taking a std::array<T, N>&& just like there is for vector and string? e.g. this one. This will make sure people can't misuse Buffer and construct it from a temporary array, which will end up making the buffer contain garbage once it goes out of scope.

[tgaldes]

should be fixed

[accelerated]

Maybe we can also have an overload for raw arrays Buffer(T(&arr)[N]) ?

[mfontanini]

Yeah, that's a good idea!

[tgaldes]

@accelerated is there a difference between construction with the raw array and the constructor Buffer(const T*, size_t size) here:
https://github.com/mfontanini/cppkafka/blob/master/include/cppkafka/buffer.h#L76

None of the code in message_builder.h uses that template from line 76, so maybe the solution is to overload payload() of BasicMessageBuilder with payload(const T* value, size_t size), and also overload the implicit conversion between ConcreteMB and MBuilder with something that will construct the buffer of the MBuilder with that same pointer and size to that no data needs to be copied.

[accelerated]

@tgaldes, the difference is simplicity and easy of use. Just like you can skip the std::vector and std::array constructors because eventually everything is convertible to a T* and a size, but they're nice to have. BasicMessageBuilder takes BufferType in all its methods and those can be a Buffer, so no need to overload with (const T*, size_t). It would make the message builder class unnecessarily complicated.

[mfontanini]

Thanks! The PR build is flapping but it's unrelated.

[tgaldes]

@accelerated Here's the addition you requested: #140