Hello class RuntimeAssoc { std::map<Emp, Mgr> std:::multimap<Mgr,Emp> public: insert(const Mgr&, const Emp&); std::pair<Mgr, Emp> find(const Mgr&); std::pair<Emp, Mgr> find(const Emp&); }; I am not sure what you mean by "direct". Do you mean compile time? The STL provides an easy way to implement mutable associations at run time (as shown above); There was an intersting article in C++ User's Journal last year containing an implemetation of a many-to-many mapping class. I think a "specific" example of what you want to do would be helpful. Craig Hicks KGK Ltd rzako23 wrote:
Are there any generic components in Boost (or elsewhere) for *directly* representing associations between classes?
Generalization, composition, aggregation and association are major ideas in the object model. Generalization can be implemented fairly directly in C++ using inheritance. Composition and aggregation can be represented directly in C++ using data members (when the number of parts in each whole is small and fixed), or using STL containers (when the number of parts in each whole is large or variable). But Standard C++ (including the STL) provides no *direct* support for representing associations, i.e., collections of links between objects in two or more classes. (David Papurt makes this point in "Inside the Object Model: The Sensible Use of C++.")
For example, the STL does not offer a way to *directly* represent the 1-to-many "Supervises" association from the Manager class to the Employee class. One would like to have links in both directions: forward links forthe employees a manager supervises and a back link to the manager each employee is supervised by. Of course, one could code this all "by hand" using a container of pointers to employees for each manager and a back pointer for each employee. But the implementation details really have little to do with managers and employees and would be pretty much the same for parents and children or teachers and students. Moreover, while not difficult, managing the forward and back links correctly (and in an exception-safe manner) is tedious. It would be nice to have templates that can be instantiated to implement specific associations.
In brief, STL containers directly support composition and aggregation but not association.
I am new to the Boost library, but was not able to find this capability in Boost. If an association library is available in Boost (or elsewhere), I would be happy to know so.
If not, is an association library something that would be worth looking into?
Thanks, Rob Zako
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