There was a long thread last year on a subject, titled "Dictionary destructing and unpacking.":

You might want to read through it and see what ideas and problems were raised then.

In that discussion, there's also a link to an older pattern matching thread:


On 4/7/2018 1:26 PM, thautwarm wrote:
We know that Python support the destructing of iterable objects.

m_iter= (_for _in range(10))
a,*b, c= m_iter

That's pretty cool! It's really convenient when there're many corner cases to handle with iterable collections. However destructing in Python could be more convenient if we support dictionary destructing.

In my opinion, dictionary destructing is not difficult to implement and makes the syntax more expressive. A typical example is data access on nested data structures(just like JSON), destructing a dictionary makes the logic quite clear:

data= {
     "direct": "some data",
     "nested": {
         "lst_data": [1,2,3],
         "int_data": 1
    "direct": direct,
     "nested": {
         "lst_data": [a, b, c],
}= data

Dictionary destructing might not be very well-known but it really helps. The operations on nested key-value collections are very frequent, and the codes for business logic are not readable enough until now. Moreover Python is now popular in data processing which must be enhanced by the entire support of data destructing.

Here are some implementations of other languages:
Elixir, which is also a popular dynamic language nowadays.

|iex> %{} = %{:a => 1, 2 => :b} %{2 => :b, :a => 1} iex> %{:a => a} = %{:a => 1, 2 => :b} %{2 => :b, :a => 1} iex> a 1 iex> %{:c => c} = %{:a => 1, 2 => :b} ** (MatchError) no match of right hand side value: %{2 => :b, :a => 1}|

And in F#, there is something similar to dictionary destructing(actually, this destructs `struct` instead) type MyRecord = { Name: string; ID: int } letIsMatchByName record1 (name: string) = matchrecord1 with| { MyRecord.Name = nameFound; MyRecord.ID = _; } whennameFound = name -> true| _ -> falseletrecordX = { Name = "Parker"; ID = 10} letisMatched1 = IsMatchByName recordX "Parker"letisMatched2 = IsMatchByName recordX "Hartono"

All of them partially destructs(or matches) a dictionary.


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