Simple OleDbDataReader question (ADO.NET)

Evil Phil

Folks
I am creating the above object in code and want to close it within a finally block, but its throwing an error e.g*:

OleDbDataReader dr;
try
{
	commandObject.CommandText = "SELECT * FROM Employees";
	dr = commandObject.ExecuteReader();
	while (dr.Read())
	{
		...
	}
}
catch (Exception e)
{
	...
}
finally
{
	if (dr!=null) // ERROR OCCURS HERE
	{
		dr.Close() 
	}
}

Now the compiler is returning an error because dr is not initialised, obviously, but I don't want to initialise it outside of the try block. What I can do is close the DataReader at the end of try, but as I said I would rather do it from within finally (or catch) in case of any errors.

Does anybody know of a way I can do this without initialising the datareader outside of try?



*Not the actual code, probably full of errors

Talliesin

You could have an unmanaged block with a pointer. Initialise the pointer to 0. Set the pointer to point to the object when you create it. Examine the pointer in the finally block.

This is an example of garbage collection making code more difficult. If you have either automatic deletion of local objects or reference-count based garbage collection you could rely on the destructor calling close() at the correct time.

bonkey

Originally posted by Evil Phil
Does anybody know of a way I can do this without initialising the datareader outside of try?

Not readily.
At the risk of asking a stupid question, why would you be averse to initialising it to null?

OleDbDataReader dr = null;

Is there some risk/high cost in doing so that would be worth the effort of going through additional contortions to try and avoid it?


jc

Evil Phil

Originally posted by bonkey

OleDbDataReader dr = null;

Works a treat. I never thought of something so simple :rolleyes: