Initialize implicitly typed local variable to IList

Question

I understand that implicitly-typed local variables must be initialized.

I know that result will be an IList so could I somehow say that var result will be an IList?

var result; //initialize to something 

if( x < 0)  
{  
    result = (from s in context.someEntity  
              where s.somecolumn = x  
              select new { c1 = s.c1,c2=s.c2}).ToList();  
}

if(x >= 0)  
{  
    result = (from s in context.someEntity  
              where s.someOtherColumn = x  
              select new { c1 = s.c1,c2=s.c2}).ToList();  
}

foreach(var y in result)  
{  
    //do something . UPDATE 1: Retrieve y.c1, y.c2

}  

Answer 1

If you know you want it to be an IList, why not just declare it as an IList?

Using var for uninitialized variables is (IMO) pretty unreadable.

Answer 2

No they can't be "var can only be used when a local variable is declared and initialized in the same statement; the variable cannot be initialized to null, or to a method group or an anonymous function."

Since you're not initializing to an interface, it won't work.

http://msdn.microsoft.com/en-us/library/bb384061.aspx

Answer 3

Do this:

var result = default(IList);

Answer 4

You might be able to do something with a ternary operation:

var list = (x < 0) ? ... : ...

but really, that would be pretty painful to read. With your code as posted I think I'd just stick with

IList result;

for readability.

Answer 5

If you are using System.Collections.Generic in your code then the only option available is

var list = (x < 0) ? ... : ...

If you try to use IList in the above scenario you will get the error Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'System.Collections.IList'. An explicit conversion exists (are you missing a cast?)

But if you are using System.Collections you can use

IList result;