Question

I have a List of a ‘complex’ type – an object with a few string properties. The List itself is a property of another object and contains objects of a variety of types, as shown in this abbreviated class structure:

Customer {    public List<Characteristic> Characteristics;    .    .    . }  Characteristic {    public string CharacteristicType;    public string CharacteristicValue; } 

I’d like to be able to collect a List of the values of a given type of Characteristics for the current Customer, which I can do in a 2-step process as follows:

List<Characteristic> interestCharacteristics = customer.Characteristics.FindAll(    delegate (Characteristic interest) {       return interest.CharacteristicType == 'Interest';    } );  List<string> interests = interestCharacteristics.ConvertAll<string>(    delegate (Characteristic interest) {       return interest.CharacteristicValue;    } ); 

That works fine, but it seems like a long way around. I’m sure I must be missing a simpler way of getting to this list, either by chaining together the FindAll() and Convert() methods, or something else I’m overlooking entirely.

For background, I’m working in .Net 2.0, so I’m limited to the .Net 2 generics, and the Characteristic class is an external dependency – I can’t change it’s structure to simplify it, and there are other aspects of the class that are important, just not in relations to this problem.

Any pointers or additional reading welcomed.

Answer 1

Here’s a generator implementation

public static IEnumerable<string> GetInterests(Customer customer) {     foreach (Characteristic c in customer.Characteristics)     {         if (c.CharacteristicType == 'Interest')             yield return c.CharacteristicValue;     } } 

sadly 3.5 extension methods and lambda are out based on your requirements but for reference here’s how to do it:

customer.Characteristics     .Where(c => c.CharacteristicType == 'Interest')     .Select(c => c. CharacteristicValue);