This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Association b/w two classes A-->B may be implemented as class A holding a reference to object B, in its instance data. Where does the association class come into picture? It is mentioned that if the association has attributes, we go for an association class. If so, is link an instance of an association class? Not clear about these concepts. Can someone please explain with simple examples. Thanks.
I may be struck by lightning for saying so, but this is very similar to relational database design when we stick attributes on an association table. Say we have people related to people - parents, children, aunts, uncles, etc. If one person has a simple collection of other people, we don't know how they are related. Maybe we make a tiny Relative object that holds a person pointer and a relationship name. Now a person can have a collection of Relatives, and we look at each object to see exactly how they are related. Man, that example used relationship too many ways. Sorry. But it gets worse. This will be hard to model: ================
I Am My Own Grandpa Many, many years ago When I was twenty three I got married to a widow Pretty as could be. This widow had a grown up daughter With flowing hair of red, My father fell in love with her And soon the two were wed. This made my dad my son-in-law And changed my very life. Now my daughter was my mother, For she was my father's wife. To complicate the matters worse Although it brought me joy, I soon became the father Of a bouncing baby boy. My little baby then became A brother-in-law to dad, And so became my uncle, Though it made me very sad. For if he was my uncle, Then that also made him brother To the widow's grown up daughter, Who of course was my step-mother. Father's wife then had a son Who kept them on the run, And he became my grandson For he was my daughter's son. My wife is now my mother's mother And it makes me blue. Because although she is my wife, She's now my grandma too. If my wife is my grandmother, Then I am her grandchild. And every time I think of it It simply drives me wild. For now I have become The strangest case you ever saw, As the husband of my grandmother, I am my own grandpa! Ray Stevens [ August 23, 2003: Message edited by: Stan James ]
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
Joined: Mar 25, 2002
Thank you Stan. The association relative class example clears the fog for me, but definitely not the lengthy example