C# Custom getter/setter without private variable

问题

I learned c# recently, so when I learned to write properties, I was taught to do it like this:

public string Name { get; set; }

Auto properties are great! But now I'm trying to do something a little more complicated, so I need to write a custom pair of accessors.

private string _Name;
public string Name {
    get { return _Name; }
    set { _Name = value }
}

I know the compiler makes a private instance variable down in it's murky depths when one uses autos, but I'm spoiled and don't want that private variable sitting around looking pointless.

Is there a way to use custom accessors without a private variable?

回答1:

Properties don't need backing variables (fields) at all. While they can be used for encapsulating simple fields you can also use them to access other data.

public Decimal GrandTotal { get { return FreightTotal + TaxTotal + LineTotal; } }

public string SomeStatus { get { return SomeMethodCall(); } }

If the goal is to simply encapsulate some field with a property you would need some sort of backing field if you are not using automatic properties.

回答2:

The answer is No, you cannot do that. It is because of recursion. (See line numbers 9 and 7):

Line 1  :   public string Name
Line 2  :   {
Line 3  :     get
Line 4  :     {
Line 5  :         return FirstName + " "  + LastName;
Line 6  :     }
Line 7  :     set
Line 8  :     {
Line 9  :         Name = value; // <-- Goes back to Line 7
Line 10 :     }
Line 11 :   }

回答3:

No, I'm afraid not. The compiler is smart enough to make this happen for you on auto-generated properties, but with standard properties I imagine the logic behind something like that would end up getting in the way and doing more harm than good.

For example, what if I create a property like this...

public int SomeValue
{
  get
  {
    return 0;
  }
}

Would the compiler (with the feature you're looking for) create a backing private variable? Why? It doesn't need one.

Additionally, if the private value isn't created until compilation time, what are you going to reference in your code:

public string Name {
  get { return _Name; }
  set { _Name = value }
}

What is _Name? What if you have another value somewhere else called _Name? Then what would the compiler call the backing value for this property? What if I need two backing values? Would the compiler be smart enough for that?

public string Name
{
  get
  {
    return string.Format("{0} {1}", _FirstName, _LastName);
  }
  set
  {
    // some parsing magic
  }
}

It's been asked before, but I imagine the answer is going to continue to be "no" for the foreseeable future.

An auto-property is syntactic shorthand for simple direct member access. (And I imagine one of its driving forces was simply to try to get people to stop creating public values directly.) Properties can grow in complexity well beyond that very easily and I personally wouldn't want the compiler trying to figure out what I can easily just tell it to do.

来源：https://stackoverflow.com/questions/8577591/c-sharp-custom-getter-setter-without-private-variable

标签

coding-style

accessor

automatic-properties