Ordered table discuss

[tst2005]

Hello,

I worked for a way to keep the original key order (#4)
@grafi-tt you also worked about it (#25).

Both approach use a special table that remind the keys on the fly during a kind of "learning phase"
after that we are using with pairs to get the keys back in the appropriate order.

My probable usual case will be

• read a json file (as a config)
• change a value
• wrote the new json file with the original key order (to have the nice git diff)

1. what is the behavior of multiple keys

{
  "a": "A",
  "zfoo": "F1",
  "b": "B",
  "zfoo": "F2",
  "z": "Z"
}

will be

{
  "a": "A",
  "zfoo": "F2",
  "b": "B",
  "z": "Z"
}

or

{
  "a": "A",
  "b": "B",
  "zfoo": "F2",
  "z": "Z"
}

2. how to change a value with or without updating the key order ?

If I want to keep the original order,
should I just make

j = decode( '{"a":"A","zfoo":"F1", "b":"B", "zfoo":"F2", "z":"Z"}' )
j.zfoo = "F3"
print(encode(j))

If I want to forget the original order for one key...
Is it possible to make :

j = decode( '{"a":"A","zfoo":"F1", "b":"B", "zfoo":"F2", "z":"Z"}' )
j.zfoo = nil -- one to remove the key (not catch by the __newindex handler)
j.zfoo = nil -- one to process the remove request by the __newindex handler
j.zfoo = "F3" -- now we can add the "zfoo" key again
print(encode(j))

to get {"a":"A", "b":"B", "z":"Z", "zfoo":"F3"}