/// <summary>
/// Modifies a strongly typed extension contained in the extensible object. Will create the strongly typed extension if it doesn't already exist.
/// </summary>
/// <typeparam name="T">Type of extensible object</typeparam>
/// <typeparam name="TExtension">Type of extension</typeparam>
/// <param name="extensibleObject">The CLR extensible object to execute the extension method on.</param>
/// <param name="modifyExtensionAction">Modification to perform on the strongly typed extension object.</param>
public static void ModifyExtension <T, TExtension>(this IExtensibleObject <T> extensibleObject, Action <TExtension> modifyExtensionAction)
where T : IExtensibleObject <T>
where TExtension : IExtension <T>, new()
{
Contract.Requires(extensibleObject != null);
Contract.Requires(modifyExtensionAction != null);
// Add extension if it does not already exist.
TExtension extension;
var extensionType = typeof(TExtension);
if (extensibleObject.TryGetExtension(extensionType, out var extensionAsInterface))
{
extension = (TExtension)extensionAsInterface;
}
else
{
extension = new TExtension();
extensibleObject.AddExtension(extension);
}
// Modify either the existing or new extension object.
modifyExtensionAction(extension);
}
/// <summary>
/// Gets an extension by extension CLR type from the extensible object. An exception is thrown if the extension does not exist.
/// </summary>
/// <param name="extensibleObject">The CLR extensible object to execute the extension method on.</param>
/// <param name="extensionType">The CLR extension type to get from the extensible object.</param>
/// <returns>Extension object contained in the extensible object.</returns>
public static IExtension <T> GetExtension <T>(this IExtensibleObject <T> extensibleObject, Type extensionType)
where T : IExtensibleObject <T>
{
Contract.Requires(extensibleObject != null);
Contract.Requires(extensionType != null);
if (extensibleObject.TryGetExtension(extensionType, out var extension))
{
return(extension);
}
var message = $"{extensibleObject.GetType().Name} has missing extension [type={extensionType.Name}]. Ensure extensible object contains extension [type={extensionType.Name}] or use the TryGetExtension method if the extension is optional.";
throw new InvalidOperationException(message);
}
/// <summary>
/// Try and get the strongly typed extension by extension CLR type from the extensible object. Returns true if the extension exists, false otherwise.
/// </summary>
/// <typeparam name="T">Type of extensible object</typeparam>
/// <typeparam name="TExtension">Type of extension</typeparam>
/// <param name="extensibleObject">The CLR extensible object to execute the extension method on.</param>
/// <param name="extension">Output parameter to capture the strongly typed extension if it exists in the extensible object.</param>
/// <returns>True if the extension exists in the extensible object, false otherwise.</returns>
public static bool TryGetExtension <T, TExtension>(this IExtensibleObject <T> extensibleObject, out TExtension extension)
where T : IExtensibleObject <T>
where TExtension : IExtension <T>
{
Contract.Requires(extensibleObject != null);
var extensionType = typeof(TExtension);
if (extensibleObject.TryGetExtension(extensionType, out var extensionAsInterface))
{
extension = (TExtension)extensionAsInterface;
return(true);
}
extension = default(TExtension);
return(false);
}
/// <summary>
/// Creates a strongly typed extension and adds it to the extensible object if it doesn't already exist. Does nothing if it already exists.
/// </summary>
/// <typeparam name="T">Type of extensible object</typeparam>
/// <typeparam name="TExtension">Type of extension</typeparam>
/// <param name="extensibleObject">The CLR extensible object to execute the extension method on.</param>
public static void CreateExtension <T, TExtension>(this IExtensibleObject <T> extensibleObject)
where T : IExtensibleObject <T>
where TExtension : IExtension <T>, new()
{
Contract.Requires(extensibleObject != null);
// Install new extension if it does not already exist.
var extensionType = typeof(TExtension);
if (extensibleObject.TryGetExtension(extensionType, out var extension))
{
return;
}
extension = new TExtension();
extensibleObject.AddExtension(extension);
}