Accessors and mutators ('get' and 'set' methods) are either a necessary evil, or poor programming, depending on your point of view.
In his book on design patterns - 'Holub on Patterns' - Allen Holub has a section in the first chapter called 'Getters and Setters Are Evil'. This is obviously an extreme view! However, he does qualify this position somewhat:
This isn't to say that your functions shouldn't return values or that "get" and "set" fuctionality is never appropriate. ... Nonetheless, get/set functions are often used inappropriately as a means of accessing otherwise private fields, and it's that usage that will give you the most trouble.
Holub characterises misuse of accesor functions as 'laziness' - deferring decisions about object interaction until later. That is to say, when the programmer first creates a class the accessor methods are created along with the attributes of the class. This is especially true for JavaBeans - which are simply Java classes with certain requirements - including the necessity for getX and setX methods for any attribute X. These 'beans' can be created semi-automatically by an IDE (you add an attribute to the bean through some GUI and the get/set methods are created for you).
Whether you agree with this assessment or not, there are other options in other languages. You can make a private inner class in C++ (see ariels writeup) that provides you with a rich attribute that you can 'get' and 'set' with the normal language syntax (e.g. 'instance.attribute = value;' instead of 'instance.setAttribute(value);'). In Python this kind of trick is simplified to use of a property to wrap a method:
def __init__(self, start, end):
self.start = start
self.end = end
return self.end - self.start
def setLength(self, length):
self.end = self.start + length
length = property(fget=getLength, fset=setLength, doc='length of the interval')
if __name__ == "__main__":
interval = Interval(1, 10)
interval.length = 10
What the 'length = property(...)' call does is associate the 'length' attribute with the two 'getLength' and 'setLength' methods (and a documentation string). As you can see from the test code at the end, accessing the pseudo-attribute 'length' effectively calls the 'getLength' method, while assigning to 'length' calls the 'setLength' method.