List.ConvertAll and Exception

Question

if ConvertAll throws an exception for one element, can I just skip this element and move on to the next element?

Answer 1

No. The exception will need to be handled somewhere. If you expect that there will be exceptions in the converter, and this is normal for the application, you should have a try-catch inside the converter (the following code example will return nullfor failed conversions):

List<string> input = new List<string> { "1", "2", "three", "4" };

List<int?> converted = input.ConvertAll(s =>
{
    int? result = null;
    try
    {
        result = int.Parse(s);
    }
    catch (Exception) { }

    return result;
});

(yes, I know what I should have used int.TryParse, but that would not throw an exception ...)

However, the use of such exceptions always gives the smell of a workaround, and I do not want to have anything in my code.

Answer 2

throwing ConvertAll, , " ". - :

public static void Main(string[] args)
{
    var integers = new List<int>() { 1, 2, -5 };
    Converter<int, string> converter = x =>
    {
        if (x < 0)
            throw new NotSupportedException();

        return x.ToString();
    };

    // This code would throw
    //var result1 = integers.ConvertAll(converter).ToArray();
    //Console.WriteLine(String.Join(Environment.NewLine, result1));

    // This code ignores -5 element
    var result2 = RobustEnumerating(integers, converter).ToArray();
    Console.WriteLine(String.Join(Environment.NewLine, result2));
}

public static IEnumerable<K> RobustEnumerating<T, K>(IEnumerable<T> input,
    Converter<T, K> converter)
{
    List<K> results = new List<K>();
    foreach (T item in input)
    {
        try
        {
            results.Add(converter(item));
        }
        catch { continue; }
    }
    return results;
}

null , .

Answer 3

, , . , , ConvertAll:

List<UnconvertedType> unconverted;

// do something to populate unconverted

List<ConvertedType> converted = unconverted.
    Where(ut => ut != null).
    ToList().
    ConvertAll<ConvertedType>(ut => ut as ConvertedType);

, , try/catch.