undefined | Better HN

0 pointsepidemian13y ago0 comments

> good OO for me usually suggests nullary constructors

I'm curious, could you please elaborate on this point? If a class has any dependency, i usually find it better to require that dependency to be passed in the constructor, so the constructed instance can always be in a valid initialized state. Why do you find nullary constructors to be good OO?

0 comments

2 comments · 1 top-level

dougk1613y ago· 1 in thread

I came off too heavy-handed there. My intention was more to just say that variables shouldn't be put in constructors if they don't have to be. So, just railing more against the pattern that Java seems to have popularized where every private variable automatically has a getter/setter and can be set through the constructor. Certainly if an object requires some initial state that can never change, passing the value in through the constructor is usually most appropriate. Even then, I sometimes like to have a nullary constructor with an init() method. Just makes certain design patterns utilizing e.g. reflection or pooling a bit easier to manage in some languages.

epidemianOP13y ago

Ok, i didn't get your point then. Well, i definitely agree on that the pattern/trend of auto-generating getters, setters and constructor parameters for every attribute in a class without considering if those attributes should be visible (or, worse, mutable) from the outside is pretty hideous.

About the nullary constructor + init() method for deserializing purposes, i don't have any strong opinion really, as long as consistency is kept throughout the code base/module that relies on that. Using Java's reflection API though, you can extract all necessary type information from non-nullary constructors in order to call them with the required dependencies, which is not essentially more complicated than instantiating the class and then setting its properties thought setter methods.

j / k navigate · click thread line to collapse