Composition??

[Germyan]

:laugh: :laugh: :laugh: I am sorry, if I did something wrong here.. but I know most people don't know the concepts they play with on day to day basis. Just thought to play on it.

led mike wrote:

problem called Germyan.

:laugh: - creative one G.

[Shog9 0]

Germyan wrote:

you are missing a important one.. when a composition is destroyed, are the objects belonging to it be destroyed as well? If the answer is NO then it is AGGREGATION.

AFAIK, there's a little bit more to it than that... but i'll bite: where in the example that i gave you did i imply that any part of my composite collection type would not be destroyed along with the collection? Granted, i did not explicitly state that it wouldn't leave bits and pieces of itself orphaned and scattered all over Creation... but i didn't think it was necessary to state such an obvious requirement.

[Germyan]

I think you said that it is a objects collection.. inside the collection you will have objects, They used a famous example to explain composition.. house vs room, can the room exist without a house?? NO Can the object exist without a collection?? YES.. so your example is not composition. I mean there are many areas, where your example violate the original definition of the composition. But, I do agree that it is the closest example, I get so far. G.

[Shog9 0]

Germyan wrote:

I think you said that it is a objects collection.. inside the collection you will have objects,

Ah, i get it. You thought i was describing the composition as being the storage of objects within the collection. But those aren't really part of the type itself, rather the type is defined as being able to store objects. The type itself is composed of an array and a tree. Those types make up the composition. They exist for the purpose of allowing the collection to fulfill its purpose; their definitions and lifetimes are tied to it.

[Liam OHagan]

No, your question was poorly worded and vague.

I have no blog...

[led mike]

Germyan wrote:

I am sorry, if I did something wrong here.

Ok, fair enough, it's a native english thing but don't use the word "poor" to describe peoples attempts to help you. They are freely giving you their time so even if you don't agree you should not make derogatory statements about their reply. The word "poor" is definitely negative in the english language.

led mike

[Nirosh]

I think both .Net and Java uses the composite relation, when define their collection classes. In that sense, the answer given here is correct. At least according to the book, but if you are against it, then,,, may be it is a good question for, who invented composition :cool:

L.W.C. Nirosh. Colombo, Sri Lanka.

[Nirosh]

Yes!! you are right, you get my 5

L.W.C. Nirosh. Colombo, Sri Lanka.

[Germyan]

Okay, I Accept it! thank for having this discussion thread. It is late here (11.00 PM) I am going to sleep now.. G.

[Shog9 0]

To be perfectly honest, i don't think it is particularly useful to draw a strong distinction here. But, if it helps you to think of your designs in these terms, then more power to you. :)

[Germyan]

Accepted!! Thanks G.

[Nirosh]

I am with you here.. I was replying to your message, but it went to the one above.

Shog9 wrote:

To be perfectly honest, i don't think it is particularly useful to draw a strong distinction

okay, then the million dollar question is.. why you have a concept called composition?

L.W.C. Nirosh. Colombo, Sri Lanka.

[Shog9 0]

Nirosh wrote:

okay, then the million dollar question is.. why you have a concept called composition?

Beats me. Why do some people spend their days coming up with names for any basic concepts? Why are there "canonical" lists of "fundamental OOP concepts" (see Ennis Ray's thread above this one)? Why are label-makers still so popular? Why does my wife keep moving the drain stopper into a basket under the sink? These are the great mysteries of The Universe, my friend. Things mortal men were not meant to understand. ;)

[Nirosh]

Much better example would be... public class RedCar { private class car { }; private class red { }; };

L.W.C. Nirosh. Colombo, Sri Lanka.

[Nirosh]

IMHO the example can easily confused the user, since it does not tell much about the definition of the Carburetor. I think, to make it complete, you need to have the Carburetor defined (as private) inside the Car class. // Composition class Car { private: Carburetor* itsCarb; public: Car() {itsCarb=new Carburetor();} virtual ~Car() {delete itsCarb;} }; // Composition [Corrected] class Car { private class Carburetor {} private: Carburetor* itsCarb; public: Car() {itsCarb=new Carburetor();} virtual ~Car() {delete itsCarb;} };

L.W.C. Nirosh. Colombo, Sri Lanka.