c# - [纯] 函数可以抛出异常吗？

Question

可以抛出异常的函数可以有[pure]属性吗？

Answer 1

根据

https://msdn.microsoft.com/en-us/library/system.diagnostics.contracts.pureattribute(v=vs.110).aspx

PureAttribute 属性

Indicates that a type or method is pure, that is, it does not make anyvisible state changes.

所以很有可能从这样的方法中抛出异常，例如

// factorial is a pure function: no state will be changed, 
// just a computation 
[Pure]
public static BigInteger Factorial(BigInteger value) {
  // We can't return infinity with BigInteger and that's why have to throw the exception 
  if (value < 0)
    throw new ArgumentOutOfRangeException("value", "value must be non-negative"); 

  ...
}

如果我将这个纯方法称为

  BigInteger result = Factorial(1000000000);

可能的结果之一是抛出 OutOfMemory 异常