Let\'s say you have a SiteUpdate and a Comment model, and you want to make Comment polymorphic. You make comment hold a \"commentable_id\" and \"commentable_type\"...
Let\'s say I have a User model and I want to have different user roles. In a single application, you can simple store the role a string, or as another model and that\'s fine.
Can I initialize a polymorphic boost::ptr_vector with boost::assign::list_of? #include <boost/ptr_container/ptr_vector.hpp>
I am using Ruby on Rails 3 and I would like to change the default type-column name used by a polymorphic association.
I have some classes that i\'d like chain m开发者_StackOverflow社区ethods of to provide a fluent style of config.
I want to make polymorphism between 4 Entities in Sybase PowerDesigner tool, bu开发者_Go百科t there is no explanation how to do this in conceptual data model.
in previous released of Mongoid (2.0.beta.20), I could pass a class type as the 2nd parameter of the .find_or_create_by block on embedded document collections.
In Why is there no base class in C++?, I quoted Stroustrup on why a common Object class for all classes is problematic in c++. In that quote there is the statement:
If I have base class: 开发者_如何学JAVA struct Base { void foo() { bar(); } virtual void bar() { } }; And derived class:
I got the classic Shape hierarchy example... struct Shape { // abstract type Shape (int x, int y); int x;
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