来自 Factory C# 的抽象类属性

Question

Consider the following abstract class :

public abstract class BuildingBase
{
    public abstract BuildingType Type { get; }

}

this class is inherited by two classes :

public class Appartment : BuildingBase
{
    public override BuildingType Type => BuildingType.Appartment;
}

public class House: BuildingBase
{
    public override BuildingType Type => BuildingType.House;
}

I have a factory that should 'build' based on the type passed :

public class Builder {
    public BuildingBase Build(BuildingType type) {
        // how to get this implemented without if / else .. case when ... etc 
    }
}

Answer 1

I'd use generics in this case, like this:

public class Builder
{
    public TBuildingBase Build<TBuildingType>()
        where TBuildingBase : BuildingBase, new()
    {
        var result = new TBuildingBase();
        ...
    }
}

But I'm not sure if you require the Enum as an input. I'm afraid that if you do want to stick with it, your choices are either an if-else construct, a constructor map like @Selvin mentioned, or using reflection (ugh).