How to restrict any one to add an extension method...

# getting-started

[Guru]

How to restrict any one to add an extension method/properties to a particular class? My team works at different location and they are trying to put similar functionality on the same class by creating extensions in two different *.kt files. They were not known that they already have similar functionality being implemented in other module unless we integrate finally to a single file/module... there is a code reusability issue here.. any suggestions ?

[karelpeeters]

Put the functionality people expect in the class itself simple smile, otherwise I don't think it's possible to limit extension functions.

[Jiddles]

I think this typically a problem with a extension functions, it’s really easy to add new ones and not know whether something similar has been implemented. Having all extensions/similar extension in the same files can help, for example:

- extensions/RxExtensions.kt
- extensions/AndroidExtensions.kt
etc.

Also having a good PR process/Danger rules/custom linting rules to limit or watch for new ones being added should help resolve the problem to some extent

[Alowaniak]

I don't think this is an 'extension functions' problem though, it could happen with static helper functions or w/e in java too
It's just a code duplication problem, I think it's important to spot things like this in reviews etc

[Guru]

I understand if this is a static function. But, with extension function its different. you are sharing your class data/properties with the function itself. it would have been nice if we could use a keyword like 'restrict' to avoid a class to have extension function. until then what you said is true. Spot things in reviews 🙂

[karelpeeters]

There's no sharing going on, extension function are pretty much just syntax sugar for static functions.