c# - 拥有通用比较器的最佳方法是什么

Question

我有很多比较器类，其中被比较的类只是检查对象的名称属性并进行字符串比较。例如:

public class ExerciseSorter : IComparer<Exercise>
{
    public int Compare(Exercise x, Exercise y)
    {
        return String.Compare(x.Name, y.Name);
    }
}

public class CarSorter : IComparer<Car>
{
    public int Compare(Car x, Car y)
    {
        return String.Compare(x.Name, y.Name);
    }
}

使此代码通用的最佳方法是什么，这样我就不需要一遍又一遍地编写冗余代码。

Answer 1

我用的是这样的:

public class AnonymousComparer<T> : IComparer<T>
{
    private Comparison<T> comparison;

    public AnonymousComparer(Comparison<T> comparison)
    {
        if (comparison == null)
            throw new ArgumentNullException("comparison");
        this.comparison = comparison;
    }

    public int Compare(T x, T y)
    {
        return comparison(x, y);
    }
}

用法:

var carComparer = new AnonymousComparer<Car>((x, y) => x.Name.CompareTo(y.Name));

如果您正在进行直接属性比较并且属性类型实现了 IComparable(例如 int 或 string)，那么，我也有这个类，使用起来更简洁:

public class PropertyComparer<T, TProp> : IComparer<T>
    where TProp : IComparable
{
    private Func<T, TProp> func;

    public PropertyComparer(Func<T, TProp> func)
    {
        if (func == null)
            throw new ArgumentNullException("func");
        this.func = func;
    }

    public int Compare(T x, T y)
    {
        TProp px = func(x);
        TProp py = func(y);
        return px.CompareTo(py);
    }
}

这个的用法是:

var carComparer = new PropertyComparer<Car, string>(c => c.Name);