foreach to LINQ to HOF progression

Three stages of a real world example.

protected virtual string ReplaceFunctions(string messageTemplate) {

    string messageBody = messageTemplate;

    Regex ex = new Regex(@"\$(?<name>[^\$]+)\$");

    MatchCollection functions = ex.Matches(messageTemplate);

    foreach(Match function in functions) {

        if(function.Groups["name"].Success) {

            messageBody = messageBody.Replace(string.Format("${0}$", function.Groups["name"].Value), "");

        }

    }

    return messageBody;

}

protected virtual string ReplaceFunctions(string messageTemplate) {

    string messageBody = messageTemplate;

    Regex ex = new Regex(@"\$(?<name>[^\$]+)\$");

    MatchCollection functions = ex.Matches(messageTemplate);

    foreach(var function in (from Match f in functions where f.Groups["name"].Success select f)) {

        messageBody = messageBody.Replace(string.Format("${0}$", function.Groups["name"].Value), "");

    }

    return messageBody;

}

protected virtual string ReplaceFunctions(string messageTemplate) {

    string messageBody = messageTemplate;

    Regex ex = new Regex(@"\$(?<name>[^\$]+)\$");

    MatchCollection functions = ex.Matches(messageTemplate);

    functions.OfType<Match>().Where(function => function.Groups["name"].Success).Select(function => messageBody.Replace(string.Format("${0}$", function.Groups["name"].Value), ""));

    return messageBody;

}