Question

Basically, I was wondering if there already exists a way to do:

Right now I have:

if (func())
{
    dictionary.add(KeyA, ValueA);
}

if (func2(myString))
{
    dictionary.add(KeyB, ValueB);
}

if (anonymous predicate)
{
    dictionary.Add(KeyC, ValueC);
}

Does there already exist a way to do:

dictionary.AddIf(KeyA, ValueA, ...)
//etc?

I added using System.Linq but it isn’t in there.

Answer 1

There’s nothing built in – I don’t find this syntax intuitive but you could write your own extension method(s) to help you out:

public static class DictionaryHelper
{
    public static void AddIf<T, U>(this Dictionary<T, U> dict,
                                   T key, 
                                   U value, 
                                   Predicate<T> pred)
    {
        if (pred(key))
            dict.Add(key, value);
    }
}

Sample usage:

Dictionary<string, string> dict = new Dictionary<string, string>();
Predicate<string> predicate =  key => { return key.Length == 3; };

dict.AddIf("foo", "bar", predicate); //foo added
dict.AddIf("tooLong", "baz", predicate); //toolong not added