Object as Key in Dictionary

Question

Hi,
In what scenarios classes or object types should be used as a key in dictionary? Is this really a good programming practice?
I think not (as I can't think of any scenario where it's must) , please explain. 
Regards, Vinay

Answer 1

 "if I have to add different type of object to one collection as key, and commands as values"
So at any point of time, one object will have one command asociated with it... I still would not like to keep it inside dictionary. I can have command be as a property of object
itself (Since the command is directly associated with the object... so there is no harm in keeping it as a part of the object itsef)...
Sorry, but in my view; this does not add any value to my programm.
Agree with one point which it says "depends on the idea and programming style"... In the real world "OOPs" I was trying to understand how using object in the dictionary gives me
any kind of distinct advantage to my programm... So for example... adding supercharged engines to a car make it more powerful than a normal engine and ofcource to add power power to the same volume of the engine u need to have supercharging (may be turbocharging
but yep... u need this)... else some one will have to increase the engine size!!!!
With all the examples given above; I always have an alternative which in my view is better... or m more convinced to implement it other way around rather than storing
the object as key.
When some one speaks about performance benefit of keeping object ("Which by nature are more complex than value types") as key rather than containing the value in the object
(though the dictionary will differentiate only on the basis of hashmap of the object)... I am not fully convinced that this will add to any performance gain over keep the object as value rather than key or rather keep the object in a non-keyvalue pair collection
if someonly has to simply loop and achieve something.
The reason why I started this debate was; since the object as a whole is quite complex; and property or unique reference is quite simple to identify the object. Why would some
one like the object to classify properties/events/or an lesser entity at all??? A cleaner approach should be to classify objects by smaller entities like color/metal/engine to identify a car class for example etc... not a car to identify an engine!
ofcource a programmer can go the other way... if wishes to!
one possible scenario would have been in this case would have been, say an IT employee class collection to represent an IT department in an organisation. though this would
have been ideal but then, it would have been really added un-necessary complexity to go on with dictionary or an custom key value collection approach in this case.
I am still thinking about an appropriate example to fit in the scenario where I could have added object as a key in keyvalue collection to add some value to my code... in terms
of performance... simplicity... flexibility!
This was just my view... your feedback is welcome.