遍历方法的参数以进行验证 [英] Iterate through method's parameters for validation purposes

问题描述

我一直认为，能够执行此类操作会很有用，例如，检查参数是否为空引用并最终引发异常.
这样可以节省一些键入时间，并且也将使您无法忘记添加检查是否添加了新参数.

I've been thinking that it would be useful to be able to do such a thing, for example, to check the parameters for null references and eventually throw an exception.
This would save some typing and also would make it impossible to forget to add a check if a new parameter is added.

推荐答案

好吧，除非您计数:

public void Foo(string x, object y, Stream z, int a)
{
    CheckNotNull(x, y, z);
    ...
}

public static void CheckNotNull(params object[] values)
{
    foreach (object x in values)
    {
        if (x == null)
        {
            throw new ArgumentNullException();
        }
    }
}

为避免数组创建失败，对于不同数量的参数，您可能会有很多重载:

To avoid the array creation hit, you could have a number of overloads for different numbers of arguments:

public static void CheckNotNull(object x, object y)
{
    if (x == null || y == null)
    {
        throw new ArgumentNullException();
    }
}

// etc

一种替代方法是使用属性声明参数不应为null，然后将 PostSharp 设置为生成适当的检查:

An alternative would be to use attributes to declare that parameters shouldn't be null, and get PostSharp to generate the appropriate checks:

public void Foo([NotNull] string x, [NotNull] object y, 
                [NotNull] Stream z, int a)
{
    // PostSharp would inject the code here.
}

诚然，我可能希望PostSharp将其转换为代码合同调用，但是我不愿意知道两个人在一起玩得如何.也许一天，我们就能写出类似Spec#的代码:

Admittedly I'd probably want PostSharp to convert it into Code Contracts calls, but I don't know how well the two play together. Maybe one day we'll be able to write the Spec#-like:

public void Foo(string! x, object! y, Stream! z, int a)
{
    // Compiler would generate Code Contracts calls here
}

...但在不久的将来不会:)

... but not in the near future :)

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