Maybe this should be discussed on the list, your are going to break API.

Note that there is also #sort and #sorted with similar copy behavior.

Also, I am not sure that basic operations should use mutexes to protect themselves by default: there is a cost when you are a single threaded user. Even in Java there are synchronized and non-synchronized versions of collections. IMHO, the protection should happen in your app, and basic collections do not have to be thread safe.

Sven

#shuffle does not use Collection>>mutexForPicking as other users of #randomForPicking demonstrate. This can lead to race conditions (found in our application).

In addition, there are now #shuffle, #shuffled, #shuffleBy: and #shuffledBy: where #shuffled and #shuffledBy: shuffle a copy and answers that. This is very confusing.

I propose a fix where #shuffled and #shuffledBy: are renamed to #copyShuffle and #copyShuffledBy: and moved to the "copying" protocol. #shuffle and #copyShuffle will use the mutex to prevent race conditions.