Question

我有recently learned如何使用lambda进行惰性评估，这使我可以这样做：

MoveTo moveToTargetCreature = 
    new MoveTo(() => parent.Context.TargetCreature);

...

public class MoveTo
{
    Func<Creature> Target { get; set; }

    public MoveTo(Func<Creature> Target)
    {
        this.Target = Target;
    }

    public Act(Creature parent)
    {
        parent.MoveTowards(Target().Position);
    }
}

...稍后调用例程Act（）方法，使生物移动到最近的目标。

当我想要做的就是检索一个变量（只是调用Target（））时这很好用，但是如果我想设置它呢？例如：

SetVariable setTargetCreatureToClosestCreature = 
    new SetVariable(parent.Context.TargetCreature, () => parent.Context.ClosestCreature);

...

public class SetVariable
{
    Creature VariableToSet { get; set; }
    Func<Creature> Target { get; set; }

    public SetVariable(Creature VariableToSet, Func<Creature> Target)
    {
        this.VariableToSet = VariableToSet;
        this.Target = Target;
    }

    public Act(Creature parent)
    {
        VariableToSet = Target(); 
        //What I want: Set "parent.Context.TargetCreature" to Target()

        //What it does: Sets the internal "VariableToSet" to Target(), but 
        //leaves "parent.Context.TargetCreature" as what it was when initialised.
    }
}

如果我选择使用Func和lambda语法，它将无法编译，因为你无法分配给方法调用。

这是什么样的合适语法？

Answer 1

也许这就是你想要的？

public class SetVariable
{
    Creature ObjectToSet { get; set; }
    Action<Creature, Creature> SetterAction { get; set; }

    public SetVariable(Creature objectToSet, Action<Creature, Creature> setterAction)
    {
        this.ObjectToSet = objectToSet;
        this.SetterAction = setterAction;
    }

    public Act(Creature parent)
    {
        this.SetterAction(parent, this.ObjectToSet);
        //the setter action would be defined as (when instantiating this object):
        //SetVariable mySet = new SetVariable(null, (target, val) => target.PropertyName = val);
        //it will set the PropertyName property of the target object to val (in this case val=null).
    }
}

塞特犬的懒惰评价

1 个答案: