重构；为应用程序域创建伪原语

Question

你将如何重构它，记住你还有几十个这样的度量要表示？这有点像将int更改为short、long或byte。泛型unit<T>？通过操作符重载进行隐式类型转换？ToType()模式？抽象基类-- IConvertible

public class lb
{
    private readonly float lbs;
    private readonly kg kgs;

    public lb(float lbs)
    {
        this.lbs = lbs;
        this.kgs = new kg(lbs * 0.45359237F);
    }

    public kg ToKg()
    {
        return this.kgs; 
    }

    public float ToFloat()
    {
        return this.lbs;
    }
}

public class kg 
{
    private readonly float kgs;
    private readonly lb lbs;

    public kg(float kgs)
    {
        this.kgs = kgs;
        this.lbs = new lb(kgs * 2.20462262F);
    }

    public float ToFloat()
    {
        return this.kgs;
    }

    public lb ToLb()
    {
        return this.lbs;
    }
}

Answer 1

我不会为每个权重创建单独的类。相反，让一个类代表一个单位，另一个类代表一个带有单位的数字：

/// <summary>
/// Class representing a unit of weight, including how to
/// convert that unit to kg.
/// </summary>
class WeightUnit
{
    private readonly float conv;
    private readonly string name;

    /// <summary>
    /// Creates a weight unit
    /// </summary>
    WeightUnit(float conv, string name)
    {
        this.conv = conv;
        this.name = name;
    }

    /// <summary>
    /// Returns the name of the unit
    /// </summary>
    public string Name { get { return name; } }

    /// <summary>
    /// Returns the multiplier used to convert this
    /// unit into kg
    /// </summary>
    public float convToKg { get { return conv; } }
};

/// <summary>
/// Class representing a weight, i.e., a number and a unit.
/// </summary>
class Weight
{
    private readonly float value;
    private readonly WeightUnit unit;

    public Weight(float value, WeightUnit unit)
    {
        this.value = value;
        this.unit = unit;
    }

    public float ToFloat()
    {
        return value;
    }

    public WeightUnit Unit
    {
        get { return unit; }
    }

    /// <summary>
    /// Creates a Weight object that is the same value
    /// as this object, but in the given units.
    /// </summary>
    public Weight Convert(WeightUnit newUnit)
    {
        float newVal = value * unit.convToKg / newUnit.convToKg;

        return new Weight(newVal, newUnit);
    }
};

这里的好处是，您可以从数据(可能是XML文件或资源)中将所有WeightUnits创建为单一对象，这样您就可以添加一个新单元，而无需更改任何代码。创建Weight对象只需按名称查找正确的单例。

Answer 2

我想我会把它变成一个struct，这是大多数原语都是的。