I had created a extension method which extended the string type in C#. // actual
ID: 644303 • Letter: I
Question
I had created a extension method which extended the string type in C#.
// actually checks if the string is empty or null and then looks up the default
// promotion code which is set in the backend admin system.
promocode.HasPromode();
I thought that was fine and dandy, but another colleague thought I should inject the method through constructor injection, which should implement a interface. I think this is overkill to have a simple lookup function to do that.
Another colleague thought that extending the string type makes it simpler to use it wrong and exposes it for the wrong purposes.
Which one is right? All solutions work fine; but some of these solutions should be the best one, or does it matter actually? It should matter, because we are having those discussions and we're trying to make the code better.
Explanation / Answer
The problem that I have with your method is that it ties a method to the string class that has nothing to do with strings in general.
It would make more sense if your extension method had something to do with strings in general, not a particular field. IsPalindrome() would make more sense as an extension method on string than HasPromode() [sic], because IsPalindrome() is applicable to any string.
Now, then...
Another colleague thought I should inject the method through constructor injection, which should implement a interface.
Er, what?
This fellow sounds like an Architecture Astronaut. While his suggestion might make sense in some context, a simple Enum.TryParse() call would suffice.
PromoCode outValue;
if (Enum.TryParse(promoCode, out outValue))
{
// string contains valid promo code.
}
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