How to expose mutable list as a readonly property in a MonoBehaviour









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Let's say I have something like this



public class BodyPart : MonoBehaviour 
private BodyPart parent;
private List<BodyPart> children;



and I want to be able to maintain both links when adding/removing children and changing parents. Ideally I would just create properties, and ensure parent gets updated when I add children and vice versa. But exposing list as a property (even a readonly property) - allows me to do



bodyPart.Children.Add(new BodyPart());


which won't call the setter, so parent field won't be updated properly.



I've seen people exposing List<...> as a property of type ReadOnlyCollection<...>, but I'm not sure if unity component system will work with such a property, and maybe there is some better way? Also - maybe IReadOnlyCollection is better?



I know I could do a hierarchy of GameObjects instead, and use the builtin parent-child relationship of unity, but I don't want my BodyParts to be full-blown GameObjects with transforms and everything, it's just a model for RPG attributes and inventory system. Also the example is simplified and ultimately I want to have more logic and several kinds of relationships between Components encoded in that model.










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  • 1




    I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
    – elgonzo
    Nov 10 at 19:41







  • 1




    Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
    – elgonzo
    Nov 10 at 19:42







  • 1




    List<T>.AsReadOnly()
    – Draco18s
    Nov 10 at 20:22














up vote
0
down vote

favorite












Let's say I have something like this



public class BodyPart : MonoBehaviour 
private BodyPart parent;
private List<BodyPart> children;



and I want to be able to maintain both links when adding/removing children and changing parents. Ideally I would just create properties, and ensure parent gets updated when I add children and vice versa. But exposing list as a property (even a readonly property) - allows me to do



bodyPart.Children.Add(new BodyPart());


which won't call the setter, so parent field won't be updated properly.



I've seen people exposing List<...> as a property of type ReadOnlyCollection<...>, but I'm not sure if unity component system will work with such a property, and maybe there is some better way? Also - maybe IReadOnlyCollection is better?



I know I could do a hierarchy of GameObjects instead, and use the builtin parent-child relationship of unity, but I don't want my BodyParts to be full-blown GameObjects with transforms and everything, it's just a model for RPG attributes and inventory system. Also the example is simplified and ultimately I want to have more logic and several kinds of relationships between Components encoded in that model.










share|improve this question



















  • 1




    I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
    – elgonzo
    Nov 10 at 19:41







  • 1




    Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
    – elgonzo
    Nov 10 at 19:42







  • 1




    List<T>.AsReadOnly()
    – Draco18s
    Nov 10 at 20:22












up vote
0
down vote

favorite









up vote
0
down vote

favorite











Let's say I have something like this



public class BodyPart : MonoBehaviour 
private BodyPart parent;
private List<BodyPart> children;



and I want to be able to maintain both links when adding/removing children and changing parents. Ideally I would just create properties, and ensure parent gets updated when I add children and vice versa. But exposing list as a property (even a readonly property) - allows me to do



bodyPart.Children.Add(new BodyPart());


which won't call the setter, so parent field won't be updated properly.



I've seen people exposing List<...> as a property of type ReadOnlyCollection<...>, but I'm not sure if unity component system will work with such a property, and maybe there is some better way? Also - maybe IReadOnlyCollection is better?



I know I could do a hierarchy of GameObjects instead, and use the builtin parent-child relationship of unity, but I don't want my BodyParts to be full-blown GameObjects with transforms and everything, it's just a model for RPG attributes and inventory system. Also the example is simplified and ultimately I want to have more logic and several kinds of relationships between Components encoded in that model.










share|improve this question















Let's say I have something like this



public class BodyPart : MonoBehaviour 
private BodyPart parent;
private List<BodyPart> children;



and I want to be able to maintain both links when adding/removing children and changing parents. Ideally I would just create properties, and ensure parent gets updated when I add children and vice versa. But exposing list as a property (even a readonly property) - allows me to do



bodyPart.Children.Add(new BodyPart());


which won't call the setter, so parent field won't be updated properly.



I've seen people exposing List<...> as a property of type ReadOnlyCollection<...>, but I'm not sure if unity component system will work with such a property, and maybe there is some better way? Also - maybe IReadOnlyCollection is better?



I know I could do a hierarchy of GameObjects instead, and use the builtin parent-child relationship of unity, but I don't want my BodyParts to be full-blown GameObjects with transforms and everything, it's just a model for RPG attributes and inventory system. Also the example is simplified and ultimately I want to have more logic and several kinds of relationships between Components encoded in that model.







c# unity3d entity-component-system






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edited Nov 10 at 19:14

























asked Nov 10 at 19:01









ajuc

482411




482411







  • 1




    I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
    – elgonzo
    Nov 10 at 19:41







  • 1




    Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
    – elgonzo
    Nov 10 at 19:42







  • 1




    List<T>.AsReadOnly()
    – Draco18s
    Nov 10 at 20:22












  • 1




    I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
    – elgonzo
    Nov 10 at 19:41







  • 1




    Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
    – elgonzo
    Nov 10 at 19:42







  • 1




    List<T>.AsReadOnly()
    – Draco18s
    Nov 10 at 20:22







1




1




I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
– elgonzo
Nov 10 at 19:41





I don't know if Unity3D will eat this, but you could implement your own (children) list type based on the IList<T> interface. Such a list would then simply keep your "normal" List<BodyPart> as a private object inside, and the respective methods of your custom list type (such as Add, Insert, Remove, the indexer setter, etc...) would not only manipulate the internal body parts list accordingly, but also manipulate the Parent property of the BodyPart objects added/removed to this list. This way you can expose it safely while keeping it mutable...
– elgonzo
Nov 10 at 19:41





1




1




Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
– elgonzo
Nov 10 at 19:42





Something along the lines of public class ChildrenList : IList<BodyPart> private List<BodyPart> _bodyPartList; ... ... interface implementation ... ...
– elgonzo
Nov 10 at 19:42





1




1




List<T>.AsReadOnly()
– Draco18s
Nov 10 at 20:22




List<T>.AsReadOnly()
– Draco18s
Nov 10 at 20:22

















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