Thanks for starting this discussion, Yangze.
My personal preference for either singleton or non-initiatable classes is
to use enum wherever it is possible, because it's briefer is safer. On the
other hand, I'm also against private constructors.
To my understanding, for most if not all
Thanks all for the valuable feedbacks!
@Gael @Dawid
Thanks for the explanation! I think you are right that this discussion
is about a non-instantiable class that contains only static methods.
@All
My major proposal is actually to stick to one of two approaches in
Flink. It seems that most devs
Hi, thanks for starting this discussion.
I am +1 for using the private constructor for util class. We don't need to
change it.
I think few libraries use the enum, such as guava, common-utils, or even
JDK, the private constructor is widely used.
I don't quite understand why a util class is an
Hi all,
First of all I very much agree with Gael. The discussion is not about a
Singleton pattern.
Secondly, similarly as @Timo and @Gael I find the pattern very
confusing. Each time I see it I have a hard time figuring out why there
are no enumerations in the enum. This is my preference though.
Hi
One small remark here: you should not call this a Singleton. For most
people, a Singleton would refer to the implementation of the GoF Singleton
pattern, where you have a single instance of the class (see for instance
the corresponding Wikipedia page:
Hi,
honstely, I find using enums is more of a hack. `enum` stands for
enumeration and is meant for listing flags or options. Using it for
singleton patterns is just abusing a concept due to certain
implementation details and less code.
I feel this topic is like using Lombok for generating
Hi,
I don't mind one way or the other.
I guess enum way is somehow safer, however did we really have any issues
with our current approach with `private` constructors? I mean, you are
mentioning that using reflections could overcome private constructors, but
is that a real concern in our code
Hi, devs,
Recently, in the PR of FLINK-19179[1], we have a discussion about how
to implement singleton pattern in Flink.
Currently, most of the utility classes implement singleton pattern
through the private constructor. Seldom utility classes leverage the
enum mechanism. From my perspective,
