Question

Using .NET 3.5, but the Select call gives the error. Shouldn’t the compiler be clever enough to infer this? If not, why not?

public IEnumerable<Customer> TableToCustomers(Table table)
{
    return table.Rows.Select(RowToCustomer);
}

private Customer RowToCustomer(TableRow row)
{
    return new Customer { ... };
}

Answer 1

The Rows property is defined as TableRowCollection Rows {get;}

public sealed class TableRowCollection : IList, ICollection, IEnumerable

It is not IEnumerable<TableRow>, so it is just IEnumerable, therefore it cannot infer the type as being TableRow.

You can do this instead:

public IEnumerable<Customer> TableToCustomers(Table table)
{
    return table.Rows.Cast<TableRow>().Select(RowToCustomer);
}