== Quote from Jerry Quinn (jlqu...@optonline.net)'s article > dsimcha Wrote: > > If anyone can think of any more, please let me know. Also, just thought of > > this > > now: I wonder if it would make sense to use some polymorphism tricks (AA > > operations are slow enough that an extra pointer dereference or virtual > > function > > call isn't going to make or break their performance) to allow > > implementations to > > be automatically and dynamically changed depending on some of the attributes > > listed above. > This is not necessarily true. If you are hammering a map of int to int, function call overhead will matter a great deal and you would like the compiler to be able to inline it. Size will also matter for huge AA tables. > On the other hand, perhaps you're willing to say that built-in AA's will not > be suitable for every case.
Yes. The builtin should handle the most common 90-95% of cases, "special" AA types in Phobos can handle another few percent, and for the last 1-2%, your problem is so specialized that you understand it way better than the language/std. lib designer that you should probably just roll your own or use some hyper-specialized 3rd party lib. > > For example, maybe binary trees are fastest for small N. (Hypothetical, > > haven't > > tested it.) Obviously for sufficiently large N hash tables will be > > fastest. We > > could create an abstract AA type that automatically switches from binary > > trees to > > hash tables when it makes sense, make this the default builtin AA, and > > expose both > > of the underlying implementations in std.containers for when the user wants > > more > > control over the details rather than DWIM. > One thing I think is important is to codify the interface to the AA implementation, so that files built with different compilers could be linked together.. I was thinking define an interface (a runtime, OO interface, the kind you can inherit from), and then define a bunch of final classes that implement that interface. This way, you can have either polymorphism (use the interface) or speed (instantiate one of the final classes directly).
