Le 30/01/13 20:53, Borislav Stanimirov a écrit :
Hello,
Boost.Mixin is a library I'm developing with the idea to someday submit it to Boost.
It is an entity-component system, with full abstraction between interface and implementation.
In short, users can define objects by combining components (often referred to from here on out as mixins). A mixin is a regular C++ class for which two macros are defined. The main thing however are the messages. Instead of getting the component with some function like `get_component` (which is possible but discouraged in the library), users deal with objects only. They can call messages (inspired by Smalltalk's messages) which are dynamically dispatched to the appropriate mixin.
The messages (also defined with macros) are the only thing needed for a user to call methods from the object's mixins. When defining a mixin, the user tells which messages it's going to implement, and when adding this mixin to the object a virtual table of sorts is filled and the object starts responding to those messages by calling the mixin's actual C++ methods.
Some of the key features are: * Multicast messages. A message that is implemented and handled by more than one mixin. See the message `trace` in the example. (As opposed to unicast messages, that are handled by a single mixin) * Object access from within the mixin. The macro `bm_this` (Boost.Mixin this). See the renderer do in the example. * "Live" object mutation by adding and removing mixins. As demonstrated in `change_rendering_system` in the example. This is done via the `object_transformer` class and is currently the only way of adding mixins to objects. * Mixin (and message) domains. The domain is a collection of mixins and messages that work together. If you create a set of mixins that will never conceivably have to exist in the same object as another set of mixins, you should use a different domain.
Here is a github link to the library: http://github.com/iboB/boost.mixin A working example can be found here: http://github.com/iboB/boost.mixin/tree/master/libs/mixin/example/basic
Hi, IIUC your library is related to the subject-role [1] but a mixin is more an aspect of an entity than a role. Could the user define a typed subjects, that is an entity that have some specific mixins? Could the user see an object restricted to some of his mixins? Best, Vicente [1] Roles :Conceptual Abstraction Theory & Practical Language Issues