c++ - Class with general and specialized attributes -

how model class general , specific attributes based on type. example have primitive class. primitive class has following general members : primitivetype, translation, rotation, plus additional fields based on primitive type.

enum primitivetype {    cylynder,    cube,    cone } class primitive {    string name;    primitivetype type;    double positionx,positiony,positionz;    double rotationx,rotationy,rotationz;    // following members if primitivetype cylynder    double height;    double radius;    //following members if primitive cube   double height;   double width;   double length;  }; 

i can of course inheritance , make primitive , cylynder , cube classes inherit primitive. classes have not polymorphic relationships between themselves, not use inheritance. need them plain structures hold attributes.

i can make composition , make cylynder , cube classes have primitive member. need store objects of cylynder,cube , cone in 1 vector. if composition how store them in 1 std::vector .

i need model structures in such way need met following requirements :

1) store objects of different types of components in 1 std::vector

2) store object of different types in easy readable , editable config file. in config file want save specialized attributes relevant specific type of primitive, , not specialized attributes primitive types. want in config file :

<primitive>  <name>primitive1</name>  <type>cylynder</type>  <positionx>0</positionx>  <!-- other common attributes here, omitted save space -->   <!-- specific primitive type attributes -->  <height> 10 </height>  <redius>5</radius> </primitive> <primitive>   <name> primitive2 </name>   <type> cube </type>   <positionx>0</positionx>   <!-- other common attributes here, omitted save space -->    <!-- specific primitive type attributes -->   <height>10</height>   <width>10</width>   <length>10</length> </primitive> 

you have many choices, e.g.:

• create 3 distinct classes , store boost::variant<cylinder, cube, cone>s in vector (conceptually that's discriminated union, boost::variant cleans , handles ugly edge cases alignment)

  • you can still use composition shared members/functionality if desired

• create 1 class enum , "fat" interface , fields (as you've started above, removing duplicate height "// many primitives" group)

  • hackish , entangled, if don't have many primitivetypes deal with, , they're not complex, may manageable , practical

• use polymorphism - seems there'll common subset of functionality can exposed, , while it's ugly dynamic_cast<> supports runtime-type-specific switching

  • your "have not polymorphic relationships between themselves, not use inheritance" isn't compelling justification avoiding it, given claimed need store types in single vector

as creating objects file content... need called "factory" - can read primitivetype config file call type-specific field-parsing , construction code.