我可以使用Expression< Func< T，bool>并可靠地查看在Func< T，bool>中引用了哪些属性? [英] Can I use Expression<Func<T, bool>> and reliably see which properties are referenced in the Func<T, bool>?

问题描述

我正在编写具有Enumerable.Where风格的东西，该谓词的形式为Func<T, bool>.如果基础T实现了INotifyPropertyChanged，那么我想对重新评估谓词更加聪明.

I'm writing something in the flavour of Enumerable.Where in that takes a predicate of the form Func<T, bool>. If the underlying T implements INotifyPropertyChanged, I'd like to be a bit more intelligent about re-evaluating the predicate.

我正在考虑将其更改为使用Expression<Func<T, bool>>，然后使用表达式树来查找谓词中使用的属性.然后，我可以让我的PropertyChanged处理程序变得更聪明.

I'm thinking about changing it to use Expression<Func<T, bool>>, and then using the expression tree to find out which properties are used in the predicate. Then I can have my PropertyChanged handler be a bit more intelligent.

我的问题:这可行吗?如果谓词很简单(例如x => x.Age > 18)，则Expression似乎包含了我需要的所有内容.在某些情况下，我将无法看到所引用的属性?

My question: is this feasible? If the predicate's simple (e.g. x => x.Age > 18), then the Expression seems to have everything I need in it. Are there scenarios where I won't be able to see which properties are referenced?

推荐答案

是的，您将能够直接看到 所引用的所有内容.当然，如果有人通过

Yes, you'll be able to see everything directly referenced. Of course, if someone passes

x => ComputeAge(x) > 18

那么您不一定会知道ComputeAge是指Age属性.

then you won't necessarily know that ComputeAge refers to the Age property.

表达式树将准确地表示lambda表达式中的内容.

The expression tree will be an accurate representation of exactly what's in the lambda expression.

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