Question

I am reading a CSV file and I would like to cache the results in an array.

This is my getter/setter:

private RedirectionRule[] RedirectionRules
{
    get
    {
        if (_redirectionRules == null)
        {
            return new RedirectionRule[MAXLENGTH];
        }

        return _redirectionRules;
    }
    set
    {
        _redirectionRules = value;
    }
}

Is this the right approach to an optimal way of caching the results?

Answer 1

I don’t think there’s much point in returning a new array in your getter when _redirectionRules is null. If you set the property in your code that parses the CSV, then it will be cached.

---

In other words, somewhere you should have a function like this to parse the CSV data (as an example, I’ve put it in the RedirectionRule class, but you could have a RedirectionRuleParser class or something like that depending on your needs):

class RedirectionRule {
    public static RedirectionRule Parse(string text) {
        // some code here to parse text for your RedirectionRule object
    }

    public static RedirectionRule[] ParseCsv(string csv) {
        string[] values = csv.Split(',');
        RedirectionRule[] rules = new RedirectionRule[values.Length];

        for (int i = 0; i < values.Length; i++) {
            rules[i] = RedirectionRule.Parse(values[i]);
        }
    }
}

Then, if you have code like this somewhere, you are caching the data:

string csv = "RuleType1,RuleType1,RuleType1";
RedirectionRules = RedirectionRule.ParseCsv(csv);

Elsewhere, where you want to access the data you have cached:

if (RedirectionRules != null) {
    // do something with your cached data
} else {
    // I don't know, throw an exception or something
}

The only thing your example code would accomplish by creating a new RedirectionRule[MAXLENGTH] array in your property’s getter would be to sneak past the RedirectionRules != null check above, thereby opening up the possibility of accessing data that looks like it’s been cached but really came out of thin air.