Question

How much information hiding is necessary? I have boilerplate code before I delete a record, it looks like this:

    public override void OrderProcessing_Delete(Dictionary<string, object> pkColumns)
    {
        var c = Connect();


        using (var cmd = new NpgsqlCommand("SELECT COUNT(*) FROM orders WHERE order_id = :_order_id", c)
            { Parameters = { {"_order_id", pkColumns["order_id"]} } } )
        {
            var count = (long)cmd.ExecuteScalar();

            // deletion's boilerplate code...
            if (count == 0) throw new RecordNotFoundException();
            else if (count > 1) throw new DatabaseStructureChangedException();
            // ...boiler plate code
        }



        // deleting of table(s) goes here...
    }

NOTE: boilerplate code is code-generated, including the “using (var cmd = new NpgsqlCommand( … )”

But I’m seriously thinking to refactor the boiler plate code, I wanted a more succint code. This is how I envision to refactor the code (made nicer with extension method (not the sole reason ;))

    using (var cmd = new NpgsqlCommand("SELECT COUNT(*) FROM orders WHERE order_id = :_order_id", c)
        { Parameters = { {"_order_id", pkColumns["order_id"]} } } )
    {
              cmd.VerifyDeletion(); // [EDIT: was ExecuteWithVerification before]
    }

I wanted the executescalar and the boilerplate code to goes inside the extension method.

For my code above, does it warrants code refactoring / information hiding? Is my refactored operation looks too opaque?

Answer 1

I would say that your refactor is extremely good, if your new single line of code replaces a handful of lines of code in many places in your program. Especially since the functionality is going to be the same in all of those places.

The programmer coming after you and looking at your code will simply look at the definition of the extension method to find out what it does, and now he knows that this code is defined in one place, so there is no possibility of it differing from place to place.