IMPLEMENTATION MATTERS contiuned

I was just working with java collections the other day and it got me thinking....

From the JavaDoc:
ArrayList
The size, isEmpty, get, set, iterator, and listIterator operations run in constant time. The add operation runs in amortized constant time, that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking).

LinkedList
All of the operations perform as could be expected for a doubly-linked list. Operations that index into the list will traverse the list from the begining or the end, whichever is closer to the specified index.



This speaks to my previous comment "Interacting components will not only be able to interface with each other through a well defined contract but also have a conversation about each others implementation details."
Why do we determine what data structures and implementations to use at design time? For a dynamic system this is not really a decision you can make at compile time, becuase (as you can see above) so much of the performance depends on the actual implementation.
Using metadata and metaprogramming we could provide this information along with our module/component/call-it-what-you-will and then the system as a whole can make a call as to what is the best way to format the data for maximum performance.

Same for my games programming / graphics card example, the graphics card can let the calling program know what types of data result in what types of performance, then the system as a whole can determine which way to format which data and even decide at runtime which underlying implementations to use (ArrayList or LinkedList).