Question

我在属性值计算中看到了非常奇怪的行为。我有一个属性HasChanged，如果它的任何依赖属性为true，则为true。但是我得到了一个结果 - 所有参数都是错误的，结果都是正确的。我正在使用MVVM Light框架，每个属性都是INotifyPropertyChanged

以下是帮助函数

    private static bool PropertyWrapper(bool value, [CallerMemberName] string callerName = "")
    {
        Logger.Debug($"[{callerName}: {value}]");
        return value;
    }

    private static T PropertyWrapper<T>(Expression<Func<T>> property)
    {
        var compiled = property.Compile();
        var result = (T)compiled.DynamicInvoke();
        Logger.Debug($"[{GetName(property)}: {result}]");
        return result;
    }

    private static string GetName<T>(Expression<Func<T>> expr)
    {
        var mexpr = expr.Body as MemberExpression;
        if (mexpr == null) return "(null)";
        if (mexpr.Member == null) return "((null))";
        return mexpr.Member.Name;
    }

这是代码

    public virtual bool HasChanged => PropertyWrapper(new[] {
        PropertyWrapper(() => TitleChanged),
        PropertyWrapper(() => EnglishTitleChanged),
        PropertyWrapper(() => OriginalTitleChanged),
        PropertyWrapper(() => PlotChanged),
        PropertyWrapper(() => OutlineChanged),
        PropertyWrapper(() => DirectorChanged),
        PropertyWrapper(() => YearChanged),
        PropertyWrapper(() => MovieRolesChanged),
        PropertyWrapper(() => GenresChanged),
        PropertyWrapper(() => CountriesChanged)
    }.Any(), "HasChanged");

    public bool YearChanged => this.state == State.Edit && this.source.MovieDescription.Year != this.clone.MovieDescription.Year;
    public bool TitleChanged => HasTitleChanges();
    public bool EnglishTitleChanged => HasEnglishTitleChanges();
    public bool OriginalTitleChanged => HasOriginalTitleChanges();
    public bool PlotChanged => HasDescriptionChanges();
    public bool DirectorChanged => HasDirectorChanges();
    public bool OutlineChanged => HasOutlineChanges();
    public bool MovieRolesChanged => HasMovieRolesChanges();
    public bool CountriesChanged => HasCountriesChanges();
    public bool GenresChanged => HasGenresChanges();

以及写入日志的内容

[TitleChanged：False]

[EnglishTitleChanged：False]

[OriginalTitleChanged：False]

[PlotChanged：False]

[OutlineChanged：False]

[DirectorChanged：False]

[YearChanged：False]

[MovieRolesChanged：False]

[GenresChanged：False]

[CountriesChanged：False]

[HasChanged：True]

看起来不太沉闷，但我无法想象它会怎样。请解释一下这种行为的原因。

Answer 1

如果集合中有任何元素，则返回不带参数的

Any。要获得您想要的内容，您必须将元素的值检查为Any谓词：

public virtual bool HasChanged => PropertyWrapper(new[] {
       //...
       }.Any(q => q), "HasChanged");

尽管集合中的所有值都为false，但Linq Any返回true

1 个答案: