独立的getter / setter方法，还是组合？

Question

While working on a project, I've been making some changes and browsing around existing framework API docs for insight.

While perusing the Kohana docs, I noticed that the getters/setters of any given class are typically combined:

public function someProperty($value = null){
    if(is_null($value){
        return $this->_someProperty;
    }
    $this->_someProperty = $value;
    return $this;
}

Rather than:

public function setSomeProperty($value){
    $this->_someProperty = $value;
    return $this;
}

public function getSomeProperty(){
    return $this->_someProperty;
}

Is there any value in doing this (the former), beyond lessening the method count of a given class? I was always under the understanding that methods (functions in general) should be more descriptive of an action. Do other experienced developers cringe, even a tiny bit, when they see this?

I was just surprised to see a popular framework use such conventions (I haven't used Kohana of course)

Answer 1

I consider this bad practise because it violates CommandQuerySeparation. Setting a value is changing state (Command). Getting a value is asking for state (Query). A method should not do both, but one thing only.

Also, it's not really obvious what a method does when it's just called username, e.g. does not have a verb, like get or set. This gets even worse in your example, because the return value is either the object itself or the property value, so its not consistent.

Moreover, getters (and setters) should be used sparingly as they will quickly convolute your API. The more getters and setters you have, the more knowledge about an object is required by collaborators of that object. If you find your objects asking other objects about their internals, chances are you misplaced the responsibilities.