object: add fixint support

[joelguittet]

Because of custom parser on one side, I have to use fixint format so that positive/negative numbers are not truncated and keep the wanted size when packing an object.

I'm not sure this feature is wanted in the core library because probably this violate the philosophy of msgpack. I have an alternative solution which consist of re-implementing msgpack_pack_object, but I propose this anyway.

[redboltz]

Thank you for sending the PR. I need some time to review it. Please wait a moment.

[redboltz]

The specification states:

https://github.com/msgpack/msgpack/blob/master/spec.md#serialization

If an object can be represented in multiple possible output formats, serializers SHOULD use the format that represents the data in the smallest number of bytes.

Essentially, msgpack_object is designed to adhere to the msgpack specification. Therefore, I believe including FIXINT types within msgpack_object is not appropriate. This could also lead to issues with implementing symmetric unpacking.

From my review of your PR, it appears that your primary requirement is packing fixints. If you need to enforce a specific fixint size during packing, you can directly call the following functions in your code:

msgpack-c/include/msgpack/pack.h

Lines 61 to 77 in 4458801

	static int msgpack_pack_uint8(msgpack_packer* pk, uint8_t d);
	static int msgpack_pack_uint16(msgpack_packer* pk, uint16_t d);
	static int msgpack_pack_uint32(msgpack_packer* pk, uint32_t d);
	static int msgpack_pack_uint64(msgpack_packer* pk, uint64_t d);
	static int msgpack_pack_int8(msgpack_packer* pk, int8_t d);
	static int msgpack_pack_int16(msgpack_packer* pk, int16_t d);
	static int msgpack_pack_int32(msgpack_packer* pk, int32_t d);
	static int msgpack_pack_int64(msgpack_packer* pk, int64_t d);
	static int msgpack_pack_fix_uint8(msgpack_packer* pk, uint8_t d);
	static int msgpack_pack_fix_uint16(msgpack_packer* pk, uint16_t d);
	static int msgpack_pack_fix_uint32(msgpack_packer* pk, uint32_t d);
	static int msgpack_pack_fix_uint64(msgpack_packer* pk, uint64_t d);
	static int msgpack_pack_fix_int8(msgpack_packer* pk, int8_t d);
	static int msgpack_pack_fix_int16(msgpack_packer* pk, int16_t d);
	static int msgpack_pack_fix_int32(msgpack_packer* pk, int32_t d);
	static int msgpack_pack_fix_int64(msgpack_packer* pk, int64_t d);

If you need to store type information somewhere (e.g., distinguishing between 0 as uint8, uint16, uint32), please consider handling this on the application side.

[joelguittet]

Hello @redboltz
Thanks for the review I agree with you, this is what I was thinking when I said "I'm not sure this feature is wanted in the core library because probably this violate the philosophy of msgpack" in my initial message.
I already done the calls to the functions you mentioned in my specific application (communicating with a server I don't manage, this is why I need fixing).
I propose to close the pull request, if somebody is looking for similar topic, there is everything here to give a direction.
Joel

[redboltz]

@joelguittet

Thank you for understanding. I believe this discussion will be valuable to others as well.