A field initializer cannot reference the non-static field, method, or property

Question

Following is my code :

private BitsManager manager;
private const string DisplayName = "Test Job";       

public SyncHelper()
{
    manager = new BitsManager();
}        

BitsJob uploadBitsJob = manager.CreateJob(DisplayName, JobType.Upload);

I am getting following error :

A field initializer cannot reference the non-static field, method, or property 'BITSIntegrationModule.SyncService.SyncHelper.manager'

The question would have been more clear had the OP included the class declaration for `SyncHelper`. — P.Brian.Mackey, Mar 04 '13 at 15:14
Don't forget to *ask a question* in your question. There's no question here, just a description of some behaviour. — Eric Lippert, Mar 04 '13 at 15:54

NDJ · Accepted Answer · 2013-03-04T15:08:41.687

11

The line

BitsJob uploadBitsJob = manager.CreateJob(DisplayName, JobType.Upload);

can't access manager because it hasn't been set to anything yet - you could move the allocation into the constructor -

private readonly BitsManager manager;
private const string DisplayName = "Test Job";       
BitsJob readonly uploadBitsJob;

public SyncHelper()
{
  manager = new BitsManager();
  uploadBitsJob = manager.CreateJob(DisplayName, JobType.Upload);
}

edited Mar 04 '13 at 15:08

answered Mar 04 '13 at 15:01

NDJ

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I would also add readonly on uploadBitsJob to make sure it can't be changed once object is created. If it makes sense. – GregC Mar 04 '13 at 15:05
Do you ask me to move `BitsJob uploadBitsJob = manager.CreateJob(DisplayName, JobType.Upload);` part into constructor as well. B'cos `manager = new BitsManager();` is already within the constructor. – Madurika Welivita Mar 04 '13 at 15:06
I've updated with a bit more code - I meant to allocate uploadBitsJob in the constructor - it can't be initialised how you're currently doing it because manager isn't set until the constructor – NDJ Mar 04 '13 at 15:07
@NDJ yes, moving into constructor works fine..But still I am little bit confuse about what happen, if you can explain this little more for me. thanks. – Madurika Welivita Mar 04 '13 at 15:10
If you were setting it to say a new BitsJob, then it would be fine - BitsJob uploadBitsJob = new BitsJob(); But, because it needs manager to be set then you need to defer the allocation until manager refers to something valid – NDJ Mar 04 '13 at 15:12
@MadurikaWelivita - the rules of C# say that you're not allowed to access any instance methods/fields/properties when you're using a field initializer. That's what the error says. That's what you've got to avoid doing. It's tricky to know how else to say it. – Damien_The_Unbeliever Mar 04 '13 at 15:15
@NDJ thanks, so, why is it not enough to keep only ` manager = new BitsManager();` within the constructor? – Madurika Welivita Mar 04 '13 at 15:16
As Damien_The_Unbeliever says, because uploadBitsJob can't be instantiated with a reliance on an instance method/field/property - and to create your uploadBitsJob you need the manager instance method CreateJob. – NDJ Mar 04 '13 at 15:19

score 3 · Answer 2 · answered Mar 04 '13 at 15:11

uploadBitsJob is declared at the class level which makes it a field. Field instances can't be used to initialize other fields.

Instead, you can declare the field without initializing it:

BitsJob uploadBitsJob;

Then initialize the field in the constructor:

public SyncHelper()
{
  manager = new BitsManager();
  uploadBitsJob = manager.CreateJob(DisplayName, JobType.Upload);//here.  Now manager is initialized
}

A field initializer cannot reference the non-static field, method, or property

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