Refract element Mixins expansion

direct-Inheritance.md

## Address (object)
- street
- city

## User (Address)
- id
- login

Nonexpanded version

[ "Address", { "id" : "User" }, {}, [
  [ "member", {}, {}, { "key" : "id" } ],
  [ "member", {}, {}, { "key" : "login" } ]
]

Copy && Expanded members solution

[ "object", { "id" : "User" }, {}, [
  [ "extend", { "ref" : "Address" }, {}, [
    [ "member", {}, {}, { "key" : "street" } ],
    [ "member", {}, {}, { "key" : "city" } ],
  ],
  [ "member", {}, {}, { "key" : "id" } ],
  [ "member", {}, {}, { "key" : "login" } ]
]

Members from parent comes first, to allow override them.

recursive.md

# A (object)
- a1
- include (B)
- a2

# B (C)
- b1

# C
- c1

Nonexpanded

[ "object", { "id" : "A" }, {}, [
  [ "member", {}, {}, { "key" : "a1" } ],
  [ "ref", {}, {}, 
   { 
      "href" : "B",
      "path" : "content"
    }
  ],
  [ "member", {}, {}, { "key" : "a2" } ]
]

Copy members

[ "object", { "id" : "A" }, {}, [
  [ "member", {}, {}, { "key" : "a1" } ],
  [ "extend", { "ref" : "B" }, {}, [
    [ "extend", { "ref" : "C" }, {}, [
      [ "member", {}, {}, { "key" : "c1" } ]
    ],
    [ "member", {}, {}, { "key" : "b1" } ],
  ],
  [ "member", {}, {}, { "key" : "a2" } ]
]

refract-mson-mixin.md

Problem

We need to solve expansion of MSON Mixins in refract spec.

Acceptable Criteria

It must preserve orders elements as they become from it original structures:

Input MSON

## Address (object)
- street
- city

## User (object)
- id
- Include Address
- login

Without expansion User MSON comes into refract:

[ "object", { "id" : "User" }, {}, [
  [ "member", {}, {}, { "key" : "id" } ],
  [ "ref", {}, {}, 
    { 
      "href" : "Address",
      "path" : ""content"
    }
  ],
  [ "member", {}, {}, { "key" : "login" } ]
]

As specified above we MUST preserve order of members in expanded element.

Copy members of referenced object into original object

[ "object", { "id" : "User" }, {}, [
  [ "member", {}, {}, { "key" : "id" } ],
  [ "extend", { "ref" : "Address" }, {}, [
    [ "member", {}, {}, { "key" : "street" } ],
    [ "member", {}, {}, { "key" : "city" } ],
  ],
  [ "member", {}, {}, { "key" : "login" } ]
]

This solution replace original referenced Element by extend and replace original element meta.id by meta.ref

I like the second solution.

There can be problem if referenced Mixin is not "ObjectElement"

Well, arrays can contain only array mixins. Objects can contain only object mixins. So, it shouldn't be a problem. But can you show an example where you think it might be?

About recursive version, there is question should member c1 reference

 [ "member", { "ref" : "C" }, {}, { "key" : "c1" } ],

• C because original place
• or B because it comes here from expansion

Another Question:

• Are we able to decompose it to original structures?
• It is required?

BTW, it seem

## User (Address)
- id
- login

Is equal definition to

## User (object)
- Include Address
- id
- login

@klokane, Can you add non-expanded version to recursive.md file? Thanks.

This is how arrays would look like:

References

## Hobbies (array)
- cricket
- gaming

## Interests (Hobbies)
- computers
- space

Non expanded

[ "Hobbies", { "id": "Interests" }, {}, [
  [ "string", {}, {}, "computers" ],
  [ "string", {}, {}, "space" ]
]]

Expanded

[ "array", { "id" : "Interests" }, {}, [
  [ "extend", { "ref" : "Hobbies" }, {}, [
    [ "string", {}, {}, "cricket" ],
    [ "string", {}, {}, "gaming" ],
  ],
  [ "string", {}, {}, "computers" ],
  [ "string", {}, {}, "space" ]
]]

---

Mixins

# A (array)
- a1
- include (B)
- a2

# B (C)
- b1

# C (array)
- c1

Expanded

[ "array", { "id" : "A" }, {}, [
  [ "string", {}, {}, "a1" ],
  [ "extend", { "ref" : "B" }, {}, [
    [ "extend", { "ref" : "C" }, {}, [
      [ "string", {}, {}, "c1" ]
    ],
    [ "string", {}, {}, "b1" ],
  ],
  [ "string", {}, {}, "a2" ]
]]

@pksunkara added