Review: std.msgpack

[Masahiro Nakagawa]

On Fri, 18 Jun 2010 23:47:38 +0900, Robert Jacques <sandford at jhu.edu>  
wrote:
>
> Second, a lot of the design and examples are very similar to the MsgPack  
> reference implementations, which are all Apache licensed. Since some of  
> these design decisions seem to not be 'D'-ish (more on that later) this  
> raises questions on just how clean room the implementation was.

The author of MessagePack allows this module to apply Boost Software  
License.

> Third, there's a lot of things that shouldn't be in the final module.
> -Should be removed:
> SimpleBuffer, VRefBuffer/vRefBuffer,
> -Redundant with other parts of phobos:
> BinaryFileWriter => LockingTextWriter, mp_Type/mp_Object/mp_KeyValue =>  
> std.variant

BinaryFileWriter removed.

mp_Object is based on std.json.JSONValue.
Variant can't have mp_pack method.
Hmm..., I check Variant again.

> -Should be moved elsewhere
> DeflateFilter/deflateFilter => zip/zlib

I agree.

> Forth, msgpack was designed to be a simple, wire level encoding of some  
> higher structure. As opposed to JSON or XML, you are not going to be  
> modifying it dynamically. The very concept that it would use buffers  
> internally, particularly the existence of the "zero-copy" buffer,  
> baffles me. (Not to mention it leaves one open to aliasing bugs.)  
> MsgPack has to decorate every single type it stores, so there is nothing  
> "zero-copy" about it. To that end, I think MsgPack/MsgUnPack should wrap  
> an input or output range as appropriate and be able to be used by a  
> general serialization library such as Orange.

If Phobos has std.serializer like Orange(or Doost.Serialization?),
I will implement MsgPackArchive.
But general serializer usually is low-performance and lacks some features.
So when user wants performance, user will use Packer and Unpacker directly.

> Other little things,
> -Why isn't nil mapped to null?

Where?

> -Why isn't there any big warnings about serializing cycles?

Oops. Current implementation can't deal with a circular reference.
I added NOTE section to Packer's comment.


Masahiro