Should make static method when possible?

Question

Consider the following class:

public class Extractor 
{

    public IService service;

    public Extractor(IService service) 
    {
        this.service = service;
    }

    public void DoSth() 
    {
        var sampleMethodInfo = this.service.GetMethodInfo();
        var version = ExtractAvailableMethodVersion(sampleMethodInfo);

        // other stuff
    }

    private int ExtractAvailableMethodVersion(MethodInfo methodInfo)
    {
        var regex = new Regex(MIGRATION_METHD_NAME_EXTRACT_VERSION);

        var matcher = regex.Match(methodInfo.Name);

        return Convert.ToInt32(matcher.Groups[1].Value);
    }
}

Resharper hints to make ExtractAvailableMethodVersion static. So my question is - should I make static method everywhere it's possible (like in the example ablove)? Is any performance difference when calling static / non-static method in such a case? Or is it only "code-style rule" to make static method when not using instance members?

Required reading: http://stackoverflow.com/questions/241339/when-to-use-static-classes-in-c-sharp — User999999, Jul 02 '14 at 07:00
I think resharper is suggesting this because it doesn't have any logic that involves an instance of `Extractor`, so static might be a viable option and save you from creating an instance purely for this method call. — Sayse, Jul 02 '14 at 07:01
I also like this answer: http://stackoverflow.com/a/2671636/87088 — Saber, Jul 02 '14 at 07:05
@Sayse - yes, but take a look that method is used only in one method and what's more - it's private, so there won't be a need to create instance only for a method call. :) Anyway - thanks, I will look closely at refrenced questions. — , Jul 02 '14 at 07:12
@pwas - you have provided a cut down example, its impossible to know how many times its called :) — Sayse, Jul 02 '14 at 07:13
@DhavalPatel how can you say `static` is a dangerous keyword? It's more restrictive, let's you do less things, so by definition it's less dangerous than NOT being static. I think what you mean is that "global mutable state accessed in secret by lying apis is dangerous". — sara, May 19 '16 at 07:18

score 3 · Accepted Answer · answered Jul 02 '14 at 06:59

You don't make methods static just when possible, you do it when it makes sense, ie. what method does is not related to specific instance, but to a class in general.

Evaluate whether this is the case here, but you are not using current instance anywhere in the method, so above might be the case.

Should make static method when possible?

1 Answers1