问题描述
我想一个常规解决方案但作为一个例子,假设我有一个的IEnumerable<串>
,其中有些可以解析为整数,而有些却不能。
I'd like a general solution but as an example, assume i have an IEnumerable<string>
, where some can be parsed as integers, and some cannot.
var strings = new string[] { "1", "2", "notint", "3" };
显然,如果我这样做选择(S = GT; int.Parse(S ,温度))
枚举的时候它会抛出异常。
Obviously if i did Select(s => int.Parse(s, temp))
it'd throw an exception when enumerated.
在这种情况下,我可以做。所有( S => int.TryParse(S,出温度))
第一,但是我想在那里我不必一一列举了 IEnumerable的一个通用的解决方案$ C $ 。C>两次
In this case i could do .All(s => int.TryParse(s, out temp))
first, however i want a general solution where i don't have to enumerate the IEnumerable
twice.
在理想情况下,我想能做到以下几点,这就要求我的魔法异常跳绳方法:
Ideally i'd like to be able to do the following, which calls my magic exception skipping method:
// e.g. parsing strings
var strings = new string[] { "1", "2", "notint", "3" };
var numbers = strings.Select(s => int.Parse(s)).SkipExceptions();
// e.g. encountering null object
var objects = new object[] { new object(), new object(), null, new object() }
var objecttostrings = objects.Select(o => o.ToString()).SkipExceptions();
// e.g. calling a method that could throw
var myClassInstances = new MyClass[] { new MyClass(), new MyClass(CauseMethodToThrow:true) };
var myClassResultOfMethod = myClassInstances.Select(mci => mci.MethodThatCouldThrow()).SkipExceptions();
我怎么能写在 SkipExceptions()
扩展方法?
为 SelectSkipExceptions一些伟大的答案()
方法,但是我不知道如果一个 SkipExceptions()
方法可以创建,沿着相同的路线为进行AsParallel()
。
Some great answers for a SelectSkipExceptions()
method, however i wonder if a SkipExceptions()
method could be created, along the same lines as AsParallel()
.
推荐答案
这个怎么样(你可能想给这个特殊的选择扩展一个更好的名字)
How about this (you might want to give this special Select Extension a better name)
public static IEnumerable<TOutput> SelectIgnoringExceptions<TInput, TOutput>(
this IEnumerable<TInput> values, Func<TInput, TOutput> selector)
{
foreach (var item in values)
{
TOutput output = default(TOutput);
try
{
output = selector(item);
}
catch
{
continue;
}
yield return output;
}
}
的 Edit5 的
的加成using语句,感谢您的意见建议
Edit5Added a using statement, thanks for the suggestion in comments
public static IEnumerable<T> SkipExceptions<T>(
this IEnumerable<T> values)
{
using(var enumerator = values.GetEnumerator())
{
bool next = true;
while (next)
{
try
{
next = enumerator.MoveNext();
}
catch
{
continue;
}
if(next) yield return enumerator.Current;
}
}
}
然而,这依赖于传入IEnumerable的尚未创建(并因此已经有抛出的异常)由前面的功能列表。例如。这很可能的不可以工作,如果你这样称呼它:选择(..)了ToList()SkipExceptions()
However this relies on the incoming IEnumerable not already being created (and therefore already having thrown Exceptions) as a list by the preceding Function. E.g. this would probably not work if you call it like this: Select(..).ToList().SkipExceptions()
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