[fpc-devel] 2 Ideas for generic TDictionary and other hash containers

[Martin Frb]

On 27/03/2025 12:33, Marco van de Voort via fpc-devel wrote:
>
> Op 27-3-2025 om 12:28 schreef Martin Frb via fpc-devel:
>>
>> which returns True, if Akey was found and therefore APtr points to 
>> existing Data, while otherwise APtr points to the empty slot, where 
>> the data can be copied to.
>>
> Without a key, you can't find the bucket or whatever where to 
> allocate, so this is not possible for all dictionaries IMHO. IOW, it 
> violates the contract with implementation details.

But in this feature, you always have the key.

You just don't have the data yet. You only create the data, if it does 
not yet exist.

Its pretty much a
   TryAdd.

But instead of having data, it adds "Default(TData)", and returns a 
pointer to the mem.
Or, if the key existed, it returns a pointer to the existing data.

Of course the pointer is only valid, until the next operation on the 
dict (or hash container).

It's just to save calculating the hash of the key twice.