我正在尝试使用嵌套类实现策略模式。
public class Restriction
{
protected SpecificRestriction _specificRestriction;
public void SetGreaterRestriction(decimal value)
{
Greater greaterRestriction = new Greater();
greaterRestriction.GreaterValue = value;
_specificRestriction = greaterRestriction;
}
public void SetLessRestriction(decimal value)
{
Less lessRestriction = new Less();
lessRestriction.LessValue = value;
_specificRestriction = lessRestriction;
}
public void SetRangeRestriction(decimal lessValue, decimal greaterValue)
{
Range r = new Range();
r.GreaterValue= greaterValue;
r.LessValue= lessValue;
_specificRestriction = r;
}
public bool Eval(decimal Value2)
{
return _specificRestriction.Eval(Value2);
}
/* Nested strategies classes */
protected abstract class SpecificRestriction
{
public abstract bool Eval(decimal Value);
}
protected class Less : SpecificRestriction
{
public decimal LessValue { get; set; }
public override bool Eval(decimal lessValue)
{
return lessValue < LessValue ;
}
}
protected class Greater : SpecificRestriction
{
public decimal GreaterValue { get; set; }
public override bool Eval(decimal greaterValue)
{
return greaterValue > GreaterValue;
}
}
protected class Range : SpecificRestriction
{
public decimal LessValue { get; set; }
public decimal GreaterValue { get; set; }
public override bool Eval(decimal mediumValue)
{
return LessValue <= mediumValue && mediumValue <= GreaterValue;
}
}
}
测试:
Restriction r = new Restriction();
r.SetLessRestriction(12);
r.Eval(13) // Return false <- Works!
r.Eval(11) // Return True <- Works!
r.SetGreaterRestriction(12);
r.Eval(13) // Return True <- Works!
r.Eval(11) // Return False <- Works!
r.SetRangeRestriction(12, 15);
r.Eval(13) // Return false <- It does not works
r.Eval(11) // Return false <- Works!
r.Eval(16) // Return false <- Works!
为什么 Range 它不起作用?我在 Range 课上做错了吗?