Eran Kampf
Eran Kampf
2 min read

The Dark Side of LINQ

I’ve been having mixed feeling for quite some time now regarding LINQ.
Sure it can make working with data sources a lot easier and it can definately save a lot of code…
But, what happens with the following C# foreach statement

List<KeyValuePair<string, string>> resultList = new List<KeyValuePair<string, string>>();
string[] paramsArray = parameters.Split(new char[] { '&' }, StringSplitOptions.RemoveEmptyEntries);
foreach (string p in paramsArray)
    int index = p.IndexOf('=');
    if (index > 0)
        string key = p.Substring(0, index);
        string value = p.Substring(index + 1);
        resultList.Add(new KeyValuePair<string, string>(key, value));

IEnumerable<KeyValuePair<string, string>> result =
    resultList.Distinct((p1, p2) => p1.Key == p2.Key);

Turns to this query:

var distinctPairs = (from keyValuePair in parameters.Split(new char[] { '&' }, StringSplitOptions.RemoveEmptyEntries)
                     let index = keyValuePair.IndexOf('=')
                     where index != -1
                     let key = keyValuePair.Substring(0, index)
                     where !string.IsNullOrEmpty(key)
                     let valueText = keyValuePair.Substring(index + 1)
                     select new { Key = key, ValueText = valueText })
                             .Distinct( (p1, p2) => (p1.Key == p2.Key) )

I don’t know about you but I find the first version a lot more approachable, readable and quicker to understand. The same code in LINQ is not shorter and looks simply looks Evil.

LINQ is like the force… It can be used to wonderful code that is simple and functional, but it also has the potential of producing cryptic code that’s hard to maintain.

Use it wisely and don’t be tempted for its dark side…