Created
October 3, 2018 18:30
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C++ MetaClass CookBook
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| // API Documentation was created based on the presentation of Herb Sutter on CppCon 2018: | |
| // https://www.youtube.com/watch?v=80BZxujhY38 | |
| // and the original propsal: | |
| // http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0707r3.pdf | |
| // and test from the implementation repo | |
| // https://github.com/asutton/clang/tree/095a810d0514ccc9b3ea66c546a2adc7384449ca/test/CXX/meta | |
| // Create a meta class | |
| template <typename T> | |
| constexpr void meta_class(T source){ | |
| // Do something with the source class | |
| } | |
| // Apply the meta class to a class | |
| class(meta_class) MyClass { | |
| }; | |
| // | |
| // Reflections | |
| // | |
| // Member function of class source | |
| source.functions(); | |
| source.member_functions(); | |
| // Get the return type of the member function | |
| function.return_type(); | |
| // Member variables of class source | |
| source.variables(); | |
| source.member_variables(); | |
| // Get the type of a member variable | |
| variable.type(); | |
| // Name of member function | |
| function.name(); | |
| // Compare member function name to a string | |
| if(std::strcmp(function.name(), "foo")==0){ | |
| // Do something on the function | |
| } | |
| // Iterate over a list of meta information | |
| for... (auto variable: source.variables){ | |
| // Do something on variable | |
| } | |
| // Check for public or private | |
| variable.is_public(); | |
| variable.is_private(); | |
| function.is_public(); | |
| function.is_private(); | |
| // Check for constructor / destructor | |
| function.is_constructor(); | |
| function.is_destructor(); | |
| // | |
| // Generation | |
| // | |
| // Generate a public member function | |
| __generate __fragment struct { | |
| int bar(int a){return a;} | |
| }; | |
| // Generate a private member function | |
| __generate __fragment class { | |
| int bar(int a){return a;} | |
| }; | |
| // Generae a public member variable | |
| __generate __fragment struct { | |
| int b; | |
| } | |
| // Generae a private member variable | |
| __generate __fragment class { | |
| int b; | |
| } | |
| // Make member variable private | |
| variable.make_private(); | |
| // Make member variable public | |
| variable.make_public(); | |
| // Make member function private | |
| function.make_private(); | |
| // Make member function public | |
| function.make_public(); | |
| // Make member function pure virtual | |
| function.make_pure_virtual(); | |
| // Generate member function with custom name and type | |
| __generate __fragment struct { | |
| typename(variable) idexpr("get_", variable)() const { | |
| return idexpr(variable); | |
| } | |
| }; | |
| // | |
| // Compiler object | |
| // | |
| // Print generate code of Test class | |
| constexpr {compiler.debug($Test);} | |
| // Assert on generated code | |
| compiler.require(!source.variables().empty(), "Need to have member variables"); |
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