英文:
Any shorthand for comparision to null or required value?
问题
在C#中，有没有一种巧妙的简写方式来实现以下代码：
list.Where(x => x.a.b == null || x.a.b == desiredIntValue)
英文:
Is there any clever shorthand in C# to this:
list.Where(x=> x.a.b == null || x.a.b == desiredIntValue)
答案1
得分: 4
在后续的C#版本中，你可以使用模式匹配和逻辑模式，特别是在这种情况下使用or操作符（假设列表是IEnumerable<>类型，因为较新的语言特性通常不支持表达式树）和常量：
const int desiredIntValue = 1;
list.Where(x => x.a.b is null or desiredIntValue)
对于非常量值，你可以这样做：
list.Where(x => (x.a.b ?? desiredIntValue) == desiredIntValue);
或者对于可空值类型：
list.Where(x => x.a.b.GetValueOrDefault(desiredValue) == desiredValue);
但不确定是否可以将其视为简写形式。
英文:
In later C# versions you can use pattern matching with logical patterns, specifically or in this case (assuming list is IEnumerable<> since the newer language features usually are not supported by expression trees) and constants:
const int desiredIntValue = 1;
list.Where(x=> x.a.b is null or desiredIntValue)
For non-constant values you can do something like:
list.Where(x => (x.a.b ?? desiredIntValue) == desiredIntValue);
Or for nullable value types
list.Where(x => x.a.b.GetValueOrDefault(desiredValue) == desiredValue);
But not sure if it can be considered as shorthand.
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