使用匿名对象+动态是否不明智？

Question

I have a class where one of the property return a List<object> . Inside that list I put a set of anonymous objects.

Then later of, I have a loop using that property's item as dynamic variable.
So my code looks like this:

private List<object> BookerTypes
{
    get
    {
        if (this.bookerTypes == null)
        {
            this.bookerTypes = new List<object>();

            var com = new SqlConnection(functions.ConnectionString).CreateCommand();
            com.CommandText = @"
SELECT
    BT.id
    , BT.name
FROM dbo.BookerTypes AS BT
ORDER BY BT.name ASC
";
            com.Connection.Open();
            try
            {
                using (var dr = com.ExecuteReader())
                {
                    while (dr.Read())
                    {
                        this.bookerTypes.Add(new { id = dr.GetInt32(0), name = dr.GetString(1) });
                    }
                }
            }
            finally
            {
                com.Connection.Close();
            }
        }

        return this.bookerTypes;
    }
}

[...]

    this.cblSBT.Items.Clear();
    foreach(dynamic bt in this.BookerTypes)
    {
        this.cblSBT.Items.Add(new ListItem()
        {
            Value = bt.id.ToString()
            , Text = bt.name
            , Selected = this.competition.SubscriptionTypes.Contains((int)bt.id)
        });
    }

Aside from the obvious lost of strongly typed type, is there any reason I should not do this?

Answer 1

The primary reason not to do this is, as you said, you've lost your static typing. There are also performance costs associated with it as well, but they're less important than the noticable problem this code has in terms of readability and maintainability.

If it turns out that you misspell or mistype a variable name you don't get compile time checking (and it's easier to do without code completion support). You also don't have any effective means of knowing, at compile time, what variables might exist in the List<object> you're given. It becomes a non-trivial task to track down the source of that list to figure out what variables might be there to use.

It is almost certainly worth the time and effort to create a new named type instead of using an anonymous type when you're in this situation. The small up front cost of creating the new class is virtually always going to pay off.

Answer 2

On top of the type-safety loss & other concerns which have already been pointed out, I feel using dynamic here is just plain wrong.

The general use-case for dynamic is for consuming data from external sources eg API/COM etc. basically scenarios where the type of information isn't already clearly defined. In your scenario, you have control over what data you are asking for and you know what type of data to expect therefore I can't really justify why you would want to use it over the benefits gained from having a clearly defined, type-safe model.

Is it unwise to use anonymous object + dynamic?

In your scenario, I would argue yes.