I have a serrious problems with this library. FSM is a design pattern and they can be spellt in a wide variety of ways. E.g state transition tables Deterministic Finite Automata, Coloured Petri Nets, and Harrel / UML state charts. There are equallly, many ways of implementing FSMs. Calling this library the FSM libray would be like submitting multimap and calling it the collections library. * What is your evaluation of the documentation? How easy (or hard) it is to understand library features? What can be improved? On the whole, the documentation looks fairly good. Some nits are that the exampls use upper case class names and can be confusing when the same name is used for a template parameter. The performance charcteristics should have been formally documented before it came forward for review. * What is your evaluation of the design? What features are supported better by alternative FSMs? What could be added (or removed) from the library? This is where I have a problem. I don't have any problem with specifying an FSM using UML notation and certainly there plenty of users that will like this. But any state chart can be collapsed into a state table and there is no good reason that event dispatch performance has to suffer. The documentation suggests that Visitor patter / double dispatch is used. and it looks like ( from the code ) that states are iterated over from outer most to inner most searching for a state willing to consume the event. The performance of event dispatch will decay linnerly with the depth of the states. I can see not good reason why event dispatch could not be achieved with constant time. The reason it is like this is that the author has used state chart concepts for the design. The state_machine class has a total of 5 conatiners ( two std::list and three std::map ) two of the maps are for history and are present even if you don't specify history. This library does not follow the C++ convention of you only pay for what you use. The author has already admitted in discussion on the list that FSMs that generate events at high speed would not be appropiate for this library. Because of the libraries design a seperate async version was needed that requires mutexs. There are many situations where I would prefer to use a re-enterent disign using flyweight singleton states. TTThis tradeoff is not possible with the current design. Because of the above I vote against inclusion of this library into boost. * Are you knowledgeable about the problem domain? I have been building FSMs for the last 20 years as they are the one of the most common patterns I use. I have build them in assembler, C, C++, and Java and none of them have ever required the space and time overhead of this library If this library is accepted into boost I will continue building my FSM by hand, use Alexsey's FSM, or SMC or even boost function. 3. Exception handling support: Several people have rightly pointed out that the rationale for the exception handling support is too thin. The problems here stem from the design. 4. On some compilers (e.g. gcc), the asynchronous part of the library and most of the tests currently cannot be compiled with RTTI turned off. It is an unnecessary overhead that is an artifact of the design. * Are there performance bottlenecks? Does the library design fit requirements of real-time systems? How is it useable for embedded systems? Is the documentation clear on performance tradeoffs? I've discussed these above. I don't believe real-time system designers would consider using this library. It is to heavey weight in both space and time, they have to jump through extra hoops such as writting a custom alloactor and custom class operator new/delete to overcome the libraries use of heap allocation. And they definately won't like non constant time event dispatch. /ikh