Custom Template Parameter to register Simple Function

[tiagokepe]

Hi all and @Yuhta,

I've been implementing the new version for the function greatest/least, see issue #3728.

I would like to register the new functions using the STL Compare class as a template parameter, like:

Greatest: ExtremeValueFunction<std::greater>
Least: ExtremeValueFunction<std::less>

This standard is used in some STL containers and structures like std::priority_queue

But I didn't find any easy way to do that, I saw that Simple Function structures have already a top-level template parameter for specific purposes.

I would appreciate if you can give me any hint.

[pedroerp]

Looks like you want to do something similar what we do with trim:

https://github.com/facebookincubator/velox/blob/main/velox/functions/prestosql/StringFunctions.h#L359

(check the specializations below)

[tiagokepe]

Thanks @pedroerp , It looks like what I needed.