OOP: Should setters be private?

Question

When writing getter/setters in classes, should the setters be private methods?

It might seem a bit redundant to have to write another method to set a variable but it seems like that might allow for a more maintainable code structure.

Answer 1

Setter is a method that is suppose to allow modifying internal state of an object without exposing that object directly. We can later include validation or other logic inside setter.

If your setter is private, you are missing the point. It's like having a door in your house that is always closed and doesn't even allow opening. Also inside the class you can simply access the field directly, why would you use a setter there?

Of course the real question is: should we have setters at all? The typical class these days holds a bunch of fields, auto-generated getters/setters and no logic. This is hardly a class. It's just a structure with awkward way of accessing elements. But that's not what you are asking for.

Answer 2

In General, I don't recommend "private" access for any member, maybe "protected". Usually, you or other programmer may require it in a descendant class.

Long Boring Descriptive Answer

Now, for accessors ("getters & setters"), its also depends on the syntax and implementation of properties on the programming language.

For Example, C++, or Java, I consider not have "real properties", and accesors, maybe required to have the same scope as the properties. (Unless using a template for properties).

C# & Delphi (Lazarus) have properties implemented, but, I don't like the way C# declare the accesors.

There are cases, where you may want a property not to be public, maybe "protected" or "package protected", and its accesors, the same access than the property.

I just work in some code in Object Pascal. Most properties where "public", and its accesors "protected", but, want to migrate that code to c++ or Java, so, I make the accesors "public", as well.

Quick Short Answer

Same access as the property, but, depends on the syntax of properties.