GetOrAddValueRef

[artelk]

It would be good to expose a method

public ref TValue GetOrAddValueRef(TKey key)

(like in DictionarySlim). That would help in case the TValue is a big struct and also to avoid double-lookups in quite common scenario like:

if (map.Get(key, out var oldValue)) // 1st
  map.Update(key, CalculateNewValue(oldValue)); //2nd
else
  map.Emplace(key, default); //2nd

vs.

ref var value = ref map.GetOrAddValueRef(key);
value = CalculateNewValue(value);

[Wsm2110]

Interesting. Ill add some api changes in the next release

[Wsm2110]

Added 'EmplaceOrUpdate' In cases where you don't know if the keyValuePair exists, this will result in 1 lookup.

[artelk]

Thank you. But it seems it doesn't really help for the scenario above. The CalculateNewValue method needs the previous value.

if (someCountersMap.Get(key, out var oldValue))
  someCountersMap.Update(key, oldValue+1);
else
  someCountersMap.Emplace(key, 1);

[Wsm2110]

I'm just wondering why you can't replace

if (someCountersMap.Get(key, out var oldValue)) someCountersMap.Update(key, oldValue+1); else someCountersMap.Emplace(key, 1);

With

SomeCountersMap.EmplaceOrUpdate(key, value)

Pretty much seems to do exactly what you suggested, or im i missing something?

Op ma 24 apr. 2023 11:53 schreef Artem Elkin @.***>:

Thank you. But it seems it doesn't really help for the scenario above. The CalculateNewValue method needs the previous value.

if (someCountersMap.Get(key, out var oldValue)) someCountersMap.Update(key, oldValue+1);else someCountersMap.Emplace(key, 1);

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[artelk]

How can you increment the existing counter value for some key in the map using EmplaceOrUpdate(key, value)? With GetOrAddValueRef it would be just:

someCountersMap.GetOrAddValueRef(key)++; // one lookup only

[Wsm2110]

Ok, Gotcha.

Op ma 24 apr. 2023 12:07 schreef Artem Elkin @.***>:

How can you increment the existing counter value for some key in the map using EmplaceOrUpdate(key, value)?

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