ITarget Class
The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The ITarget class is the interface for all target blocks. Target blocks consume messages offered to them by ISource blocks.
Syntax
template<class T>
class ITarget;
Parameters
T
The data type of the payload within the messages accepted by the target block.
Members
Public Typedefs
| Name | Description |
|---|---|
filter_method |
The signature of any method used by the block that returns a bool value to determine whether an offered message should be accepted. |
type |
A type alias for T. |
Public Constructors
| Name | Description |
|---|---|
| ITarget::~ITarget Destructor | Destroys the ITarget object. |
Public Methods
| Name | Description |
|---|---|
| ITarget::propagate Method | When overridden in a derived class, asynchronously passes a message from a source block to this target block. |
| ITarget::send Method | When overridden in a derived class, synchronously passes a message to the target block. |
| ITarget::supports_anonymous_source Method | When overridden in a derived class, returns true or false depending on whether the message block accepts messages offered by a source that is not linked to it. If the overridden method returns true, the target cannot postpone an offered message, as consumption of a postponed message at a later time requires the source to be identified in its sourse link registry. |
Protected Methods
| Name | Description |
|---|---|
| ITarget::link_source Method | When overridden in a derived class, links a specified source block to this ITarget block. |
| ITarget::unlink_source Method | When overridden in a derived class, unlinks a specified source block from this ITarget block. |
| ITarget::unlink_sources Method | When overridden in a derived class, unlinks all source blocks from this ITarget block. |
Remarks
For more information, see Asynchronous Message Blocks.
Inheritance Hierarchy
ITarget
Requirements
Header: agents.h
Namespace: concurrency
ITarget::~ITarget Destructor
Destroys the ITarget object.
virtual ~ITarget();
ITarget::link_source Method
When overridden in a derived class, links a specified source block to this ITarget block.
virtual void link_source(_Inout_ ISource<T>* _PSource) = 0;
Parameters
_PSource
The ISource block being linked to this ITarget block.
Remarks
This function should not be called directly on an ITarget block. Blocks should be connected together using the link_target method on ISource blocks, which will invoke the link_source method on the corresponding target.
ITarget::propagate Method
When overridden in a derived class, asynchronously passes a message from a source block to this target block.
virtual message_status propagate(
_Inout_opt_ message<T>* _PMessage,
_Inout_opt_ ISource<T>* _PSource) = 0;
Parameters
_PMessage
A pointer to the message object.
_PSource
A pointer to the source block offering the message.
Return Value
A message_status indication of what the target decided to do with the message.
Remarks
The method throws an invalid_argument exception if either the _PMessage or _PSource parameter is NULL.
ITarget::send Method
When overridden in a derived class, synchronously passes a message to the target block.
virtual message_status send(
_Inout_ message<T>* _PMessage,
_Inout_ ISource<T>* _PSource) = 0;
Parameters
_PMessage
A pointer to the message object.
_PSource
A pointer to the source block offering the message.
Return Value
A message_status indication of what the target decided to do with the message.
Remarks
The method throws an invalid_argument exception if either the _PMessage or _PSource parameter is NULL.
Using the send method outside of message initiation and to propagate messages within a network is dangerous and can lead to deadlock.
When send returns, the message has either already been accepted, and transferred into the target block, or it has been declined by the target.
ITarget::supports_anonymous_source Method
When overridden in a derived class, returns true or false depending on whether the message block accepts messages offered by a source that is not linked to it. If the overridden method returns true, the target cannot postpone an offered message, as consumption of a postponed message at a later time requires the source to be identified in its sourse link registry.
virtual bool supports_anonymous_source();
Return Value
true if the block can accept message from a source that is not linked to it false otherwise.
ITarget::unlink_source Method
When overridden in a derived class, unlinks a specified source block from this ITarget block.
virtual void unlink_source(_Inout_ ISource<T>* _PSource) = 0;
Parameters
_PSource
The ISource block being unlinked from this ITarget block.
Remarks
This function should not be called directly on an ITarget block. Blocks should be disconnected using the unlink_target or unlink_targets methods on ISource blocks, which will invoke the unlink_source method on the corresponding target.
ITarget::unlink_sources Method
When overridden in a derived class, unlinks all source blocks from this ITarget block.
virtual void unlink_sources() = 0;