Question

if i have a private property in a class, i’m wondering what technically the difference is between the following three scenarios (memory usage, usability, best practice, etc):

class testClass {      private string myString1 = 'hello';       private string myString2 { get { return 'hello'; } }       private string myString3() { return 'hello'; } } 

apart from obviously being able to set the value in myString1 and not in myString2 or myString3, i’m wondering more about how these differ in terms of efficiency?

Answer 1

All these methods are very different in terms of what they get compiled to, though very much similar in terms of use. I’ll try to summarise the differences in brief:

1. This is a simple private instance variable. It’s easily going to be the most efficient when referencing.

2. This is a read-only property (i.e. a get but no set accessor).

3. This is a normal parameterless function. I suspect you’re just offering these examples purely as a point of comparison, and realise that such a function is totally useless (as are private properties, in almost all cases). The layout (i.e. everything on one line) is also rather horrible.

Methods 2 and 3 are going to be equally inefficient compared to 1 in that they both involve the overhead of function calls. I don’t know by memory the CIL code that they all compile to (maybe someone else can produce that), but they certainly involve a few more instructions, whereas referencing myString1 ought to only require a single instruction in CIL.

Not sure I can make a very useful comment on best practice without knowing more about the context, but method 2 (i.e. a private property) is generally seen as quite useless. The third method should never be used in my opinion (it’s begging to be turned into a property). I think what you really want is just a plain old private variable, so definitely go for the first declaration. Public values should always be accessed as properties rather than variables in classes (i.e. a private/protected backing variable to a property), but that is slightly unrelated to your question. (You could find plenty of resources discussing the matter in a quick search anyway.) Finally, note that if your ‘property’ is going to be read-only (i.e. not modified at any point), you really want to use a constant, i.e. private const string myString1 = 'hello';.

Hope that helps clarify things a bit.