CountTable inconsistencies between keys() and len() after setting value to 0

[andreas-wilm]

After setting a CountTable value to 0 (in lieu of a missing del() call!?), the key appears from keys() as expected, but is still accounted for in len()

Example

import tables

let myString = "abracadabra"
var letterFrequencies = toCountTable(myString)

echo "BEFORE set 0"
echo letterFrequencies
echo "len ", len(letterFrequencies)
for k, v in letterFrequencies.pairs():
  echo k, ":", v

echo "AFTER set 0"
letterFrequencies['a'] = 0
echo letterFrequencies
echo "len ", len(letterFrequencies)
for k, v in letterFrequencies.pairs():
  echo k, ":", v

Current Output

BEFORE set 0
{'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2}
len 5
a:5
b:2
c:1
d:1
r:2
AFTER set 0
{'b': 2, 'c': 1, 'd': 1, 'r': 2}
len 5
b:2
c:1
d:1
r:2

Expected Output

BEFORE set 0
{'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2}
len 5
a:5
b:2
c:1
d:1
r:2
AFTER set 0
{'b': 2, 'c': 1, 'd': 1, 'r': 2}
len 4
b:2
c:1
d:1
r:2

Possible Solution

NA

Additional Information

See also https://forum.nim-lang.org/t/5639#35021 and https://stackoverflow.com/questions/59160984/remove-key-from-counttable-in-nim

$ nim -v
Nim Compiler Version 1.0.4 [Linux: amd64]

[andreas-wilm]

As an aside for later reference: CountTable.del() was introduced recently in 4aeb51141