Question

For private class variables, which one is preferred?

If you have a property like int limit, you want it to be:

int Limit {get; set;}

and use it inside the class, like so:

this.Limit

Is there a reason to use it or not use it? Maybe for performance reasons?

I wonder if this is a good practice.

Answer 1

For a private member, I only make it a property when getting and/or setting the value should cause something else to occur, like:

private int Limit
{
   get
   {
       EnsureValue();
       return this._limit;
   }
}

Otherwise, fields are fine. If you need to increase their accessibility, it’s already a big enough change that making it a property at that point isn’t a huge deal.

Edit: as Scott reminds us in the comments, side effects in properties can often cause more pain than anything else. Don’t violate Single Responsibility and limit property logic to consistent, logical operations on the value only that must be done at the gate – such as lazy loading (as in the example above), transforming an internal structure into a publicly-useful format, etc.