C# Accessor and initialization

Question

How can we combine c# accessor declaration and initialization

List<string> listofcountries= new List<string>();
and 
List<string>listofcountries {get;set;}

Is there a way to combine these to statements ?

currently I am doing that just curious if there is some other / better way out — knowledgeseeker, Sep 05 '14 at 12:34
http://stackoverflow.com/questions/40730/how-do-you-give-a-c-sharp-auto-property-a-default-value — eran otzap, Sep 05 '14 at 12:36

score 7 · Answer 1 · answered Sep 05 '14 at 12:36

7

You can't at the moment. You will be able to in C# 6:

List<string> Countries { get; set; } = new List<string>();

You can even make it a read-only property in C# 6 (hooray!):

List<string> Countries { get; } = new List<string>();

In C# 5, you can either use a non-automatically-implemented property:

// Obviously you can make this read/write if you want
private readonly List<string> countries = new List<string>();
public List<string> Countries { get { return countries; } }

... or initialize it in the constructor:

public List<string> Countries { get; set; }

public Foo()
{
    Countries = new List<string>();
}

answered Sep 05 '14 at 12:36

Jon Skeet

1,421,763
867
9,128
9,194

i'm looking at an answer by you where you said it's 5 and higher : http://stackoverflow.com/questions/169220/initializing-c-sharp-auto-properties – eran otzap Sep 05 '14 at 12:38
2

@eranotzap: Um, no - read it carefully. It says it's *not* available up to and including C# 5, but it's planned to be available in C# 6. – Jon Skeet Sep 05 '14 at 12:38
o'k sorry , my mistake – eran otzap Sep 05 '14 at 12:39

score 0 · Answer 2 · answered Sep 05 '14 at 12:35

0

Only in C# 6.

what i usually like to do is :

  private List<string> list;
  public List<string> List
  {
     get
     {
         if(list == null)
         {
            list = new List<string>();
         }

         return list;  
     }
  }

answered Sep 05 '14 at 12:35

eran otzap

12,293
20
84
139

Chris Pratt · Answer 3 · 2014-09-05T12:43:40.003

0

You could either use the constructor, or create a custom getter/setter:

Constructor

public class Foo
{
    public Foo()
    {
        listofcountries = new List<string>();
    }

    public List<string> listofcountries { get; set; }
}

Custom Getter/Setter

private List<string> _listofcountries;
public List<string> listofcountries
{
    get
    { 
        if (_listofcountries == null)
        {
            _listofcountries = new List<string>();
        }
        return _listofcountries;
    }
    set { _listofcountries = value; }
}

For what it's worth, convention is to have public properties be camel-cased: ListOfCountries rather than listofcountries. Then the private instance variable for the property would also be camel-cased, but with the first letter lowercase: listOfCountries rather than _listofcountries.

UPDATE Skeet FTW, as usual. Once C# 6 hits, then his answer will be the best way, hands down. In lesser versions, you're stuck with the methods I posted.

edited Sep 05 '14 at 12:43

answered Sep 05 '14 at 12:36

Chris Pratt

232,153
36
385
444

Your custom getter is inappropriate, as if it's null and you use the getter twice, you'll get two different lists - you'd want to assign to `_listofcountries`. – Jon Skeet Sep 05 '14 at 12:38
Right. That's what I get for posting too quickly. Fixed. – Chris Pratt Sep 05 '14 at 12:47
There's also the "write a custom property, but don't bother making it lazy" approach, which means it's just a two-liner... there's no indication that the OP *wants* the allocation to be lazy. – Jon Skeet Sep 05 '14 at 12:49

score 0 · Answer 4 · answered Sep 05 '14 at 12:36

0

Not in the same statement. You can do it in the constructor body though

answered Sep 05 '14 at 12:36

Adrian Zanescu

7,907
6
35
53

C# Accessor and initialization

4 Answers4