[Python] Python Dictionary remove_from_dict does not work with tuple as dictionary key.

[Freymaurer]

Assume the following:

#r "nuget: Fable.Core, 4.2.0"

open System.Collections.Generic

let my_dict_min = Dictionary((Map [for i in 0..10 do yield i, sprintf "Number: %i" i]))

let my_dict = Dictionary((Map [for i in 0..10 do yield (i,i), sprintf "Number: %i" i]))

Getting values from key will work for both dictionary, but when i try to remove values by key it will throw an error for tuple as key.

I checked the transpiled code and saw that my_dict.Remove((0,0)) gets transpiled to: remove_from_dict(my_dict, (0, 0)).

Then checking the fable_library source files we find:

def remove_from_dict(di: dict[_K, Any], k: _K) -> bool:
    if k in di:
        del di[k]
        return True

    return False

I copied the dictionary creation code to a jupyter notebook and tested the del part of remove_from_dict and it turns out that it fails as soon as del is called with a tuple as key for the dictionary

As Fable.Python is pretty "cutting edge" i will provide the f# source code without a REPL. It was transpiled using dotnet tool fable 4.6.0

// source code
#r "nuget: Fable.Core, 4.2.0"

open System.Collections.Generic

let my_dict_min = Dictionary((Map [for i in 0..10 do yield i, sprintf "Number: %i" i]))

let my_dict = Dictionary((Map [for i in 0..10 do yield (i,i), sprintf "Number: %i" i]))

let v = my_dict.[0,0] // This will run

printfn "GET: %A" v

my_dict_min.Remove(0) // This will run
my_dict.Remove((0,0)) // This will fail

let removeEven() =
  let mutable rmvKeys = ResizeArray()
  for KeyValue((i1,i2),v) in my_dict do
      // Remove cells of column
      if i1%2 = 0 then
          rmvKeys.Add((i1,i2)) // add to seperate collection first. Fable.Python does not like altering dictionary while iterating over it.
  printfn "END ADD LIST"
  for key in rmvKeys do
      my_dict.Remove(key) |> ignore

removeEven()

printfn "%A" my_dict

@HLWeil

[andreaschrader]

Del removes a referencefor a namespace. The reference needs to be there.

I guess the reason is that the tuple is not present as a key int he dictionary.
If you use your_dict.pop(your_tuple_key), this should not be a problem.
Does this work?

[MangelMaxime]

@andreaschrader I tried your solution, but it doesn't work

raceback (most recent call last):
  File "/workspaces/Fable/src/Fable.Cli/../quicktest-py/quicktest.py", line 45, in <module>
    main(sys.argv[1:])
  File "/workspaces/Fable/src/Fable.Cli/../quicktest-py/quicktest.py", line 39, in main
    ignore(remove_from_dict(dic_1, (1, 2)))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspaces/Fable/src/quicktest-py/fable_modules/fable_library/map_util.py", line 81, in remove_from_dict
    di.pop(k)
    ^^^^^^
AttributeError: 'Dictionary' object has no attribute 'pop'

Del removes a referencefor a namespace. The reference needs to be there.

I am not exactly sure what you mean by that, but del is called only if the key is present in the dictionary.

def remove_from_dict(di: dict[_K, Any], k: _K) -> bool:
    if k in di:
        del di[k]
        return True

    return False

[dbrattli]

The problem here is that the Dictionary class is transpiled from F# so it doesn't currently implement __delitem__ for remove. I'll make a fix for this.