重构方法 - 传入属性名称

Question

我想知道是否可以将这两种方法重构为一种。 唯一的区别在于Select方法; 一个使用BaselineSetNumber，另一个使用ComparisonSetNumber。

public Set LoadBaselineSet(ObservableCollection<Set> sets)
{
    using (var db = _contextFactory.GetContext())
    {
        var setNumber =
            db.Users.Where(x => x.Login == Environment.UserName)
                    .Select(x => x.BaselineSetNumber).Single(); // !!! HERE
        return sets.Single(x => x.SetNumber == setNumber);
    }
}

public Set LoadComparisonSet(ObservableCollection<Set> sets)
{
    using (var db = _contextFactory.GetContext())
    {
        var setNumber =
            db.Users.Where(x => x.Login == Environment.UserName)
                    .Select(x => x.ComparisonSetNumber).Single(); // !!! HERE
        return sets.Single(x => x.SetNumber == setNumber);
    }
}

我想要一个我可以像LoadSet(sets, BaselineSetNumber);一样调用的方法LoadSet(sets, BaselineSetNumber); 或LoadSet(sets, ComparisonSetNumber);

Answer 1

是的，这可以通过创建更高阶的函数来实现 。 您的新代码看起来像这样：

public Set LoadBaselineSet(ObservableCollection<Set> sets)
{
    return LoadSet(sets, (x) => x.BaselineSetNumber)
}

public Set LoadComparisonSet(ObservableCollection<Set> sets)
{
    return LoadSet(sets, (x) => x.ComparisonSetNumber)
}

public Set LoadSet(ObservableCollection<Set> sets, Func<dbObject, Int> elementIdentity){
        using (var db = _contextFactory.GetContext())
    {
        var setNumber =
            db.Users.Where(x => x.Login == Environment.UserName)
                    .Select(elementIdentity).Single(); // !!! HERE
        return sets.Single(x => x.SetNumber == setNumber);
    }
}