I started to wonder about that when I was looking for an equivalent method in Ruby. Apparently, Ruby doesn’t come with such a method built-in, but you can add it very easily by using Ruyb’s monkey patching abilities.
This is odd, because Ruby is the greatest language and has everything you possibly need (and IronRuby is even better! :) ). So why isn’t there an IsNullOrEmpty-like method? Well, they might just didn’t think it was important enough. And there might be a different answer, maybe the decision has other reasons below the surface.
Several developers have discussed the String.IsNullOrEmpty issue over the years. Some say it’s good, some say it’s bad and some even say it’s hazardous to your code (because of a bug it has).
For me, I go with Ruby’s approach (unless they didn’t add it because of time constraints). Most of the time there will be a big difference between a null string object and an empty string object. Therefore, I think that String.IsNullOrEmpty() should be avoided as much as possible and the application should have a convention of how uninitialized strings should look like – nulls or String.Empty.
For example, say you need to validate some input and String.Empty is sent to you. How do you know if the string is an uninitialized string or a real input? saying that null is the convention would have solved this confusion.
I know there are cases where you have to use IsNullOrEmpty. For example, when using 3rd party components that you are not aware of their uninitialized string convention (if such exists…). This is why I don’t rule out IsNullOrEmpty entirely. I do say that wherever you can, do not use it and prefer str == null to spot uninitialized strings.
By the way, deciding that only null is the convention for uninitialized strings can also improve your application performance since str == null is faster than String.IsNullOrEmpty(str) in about 35%. However, you’ll notice an improvement only if you’re doing billions of String.IsNullOrEmpty calls, so don’t panic right away.
In conclusion, String.IsNullOrEmpty is there for convenience reasons. Sometimes with convenience comes tranquility, so make use of it wisely!
Just a final addition, Ruby on Rails adds a blank? method to Ruby which provides the equivalent to String.IsNullOrEmpty method in C#. So, if Ruby does not contain everything you need, Ruby on Rails surely does! :)
So what do you think, IsNullOrEmpty is good or bad for your application?
All the best,