• Anand Krishnamoorthi <anand.shankar.k gmail.com> Apr 24 2007
• Anand Krishnamoorthi <anand.shankar.k gmail.com> Apr 24 2007

Hi,

I've been working on a `Visitor' generation library.
The main advantages being aimed for are:

1) N number of arguments and return type ( templatized )
2) Prevent coupling between classes
3) Easy to add new classes
4) Not having to declare a Visitor interface with visit methods
5) Efficient dispatch: equivalent to a virtual function call
( normally a visitor requires 2 virt calls; acyclic visitor
requires a dynamic cast )
6) Add new visit methods at runtime

One drawback includes having to register each visit method.
But this is also allows runtime flexibility.

A visitor can be created as a singleton if needed.

The code has been developed using VC++ 8.0.
The implementation techniques include assigning tags to classes
on the fly, building virtual table internally, creating thunk
functions, a cast policy etc.

Cvisitor.h contains the library.
test1.cpp contains an example for a Shape heirarchy.

Please feel free to discuss the code.
Comments and suggestions are welcome.

Thanks,
Anand.

I'll test it in Digital Mars C++, G++ soon and post the results.

Anand.