Following on from my previous post on naming things, here's a few words about naming dictionaries.
I've been working with a codebase recently which makes a lot of use of dictionaries, and myself often find them useful when implementing a kind of strategy pattern where the keys are values you might otherwise have in a switch statement, something like this:
public class Foo { private readonly Dictionary<CustomerType, Action<Customer>> _customerActionsByType;
public Foo()
{
\_customerActionsByType = new Dictionary<CustomerType, Action<Customer\>>
{
{ CustomerType.Anonymous, DoAnonymousCustomerStuff },
{ CustomerType.Registered, DoRegisteredCustomerStuff }
};
}
public void DoCustomerStuff(Customer customer)
{
\_customerActionsByType\[customer.Type\].Invoke(customer);
}
private static void DoAnonymousCustomerStuff(Customer customer)
{
}
private static void DoRegisteredCustomerStuff(Customer customer)
{
}
}
Through working with lots of dictionaries, I've started naming them as in the example above - [value type]By[key type]. So, for other, possibly-gratuitous examples:
- sectionsById
- eventsByDayOfTheWeek
- ordersByCustomer
…you get the idea. I like this naming pattern for dictionaries because it includes both the things the dictionary structure exposes to the program - the types of the keys and the values - in a way which also describes the purpose of the object. It doesn't contain the word 'dictionary' because that's an implementation detail.