ReadCondition objects are conditions specifically dedicated to read operations and attached to one DataReader.
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#include "ReadCondition.hpp"
Inherits dds::core::cond::Condition.
Inherited by dds::sub::cond::QueryCondition.
ReadCondition objects are conditions specifically dedicated to read operations and attached to one DataReader.
ReadCondition objects allow an application to specify the data samples it is interested in (by specifying the desired sample states, view states, and instance states). (See the parameter definitions for DataReader's read/take operations.) This allows the middle-ware to enable the condition only when suitable information is available. They are to be used in conjunction with a WaitSet as normal conditions. More than one ReadCondition may be attached to the same DataReader.
See the WaitSet examples for some examples.
Although the WaitSet examples use the StatusCondition, the basic usage of this Condition with a WaitSet is the same.
- See also
- dds::core::cond::Condition
-
Status concept
-
WaitSet concept
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Subscription concept
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WaitSet examples
Definition at line 63 of file ReadCondition.hpp.
◆ ReadCondition() [1/3]
Create a dds::sub::cond::ReadCondition associated with a DataReader.
The ReadCondition can then be added to a dds::core::cond::WaitSet so that the application can wait for specific status changes that affect the Entity.
State Masks.
The result of the ReadCondition depends on the selection of samples determined by three masks:
- DataState::sample_state() is the mask, which selects only those samples with the desired sample states SampleState::read(), SampleState::not_read() or SampleState::any().
- DataState::view_state() is the mask, which selects only those samples with the desired view states ViewState::new_view(), ViewState::not_new_view() or ViewState::any().
- DataState::instance_state() is the mask, which selects only those samples with the desired view states InstanceState::alive(), InstanceState::not_alive_disposed(), InstanceState::not_alive_no_writers(), InstanceState::not_alive_mask() or InstanceState::any(). See also Status Concept.
- Parameters
-
| dr | The DataReader to associate with the ReadCondition. |
| status | A mask, which selects only those samples with the desired sample/view/instance states. |
- Exceptions
-
◆ ReadCondition() [2/3]
◆ ReadCondition() [3/3]
◆ data_reader()
◆ dispatch()
| void dds::core::cond::Condition::dispatch |
( |
| ) |
|
|
inherited |
Dispatches the functor that have been registered with the Condition.
The Condition has to have been triggered for the functor will be called by this function.
- Returns
- void
- Exceptions
-
◆ handler() [1/2]
template<typename Functor >
| void dds::core::cond::Condition::handler |
( |
const Functor & |
func | ) |
|
|
inherited |
Registers a functor as custom handler with this Condition.
The supplied functor will be called when this Condition is triggered and either the dds::core::cond::Condition::dispatch() is called or the dds::core::cond::WaitSet::dispatch() on the WaitSet to which this Condition is attached to.
- Template Parameters
-
| Functor | The functor to be called when the StatusCondition triggers. |
- Returns
- void
- Exceptions
-
◆ handler() [2/2]
template<typename Functor >
| void dds::core::cond::Condition::handler |
( |
Functor & |
func | ) |
|
|
inherited |
Registers a functor as custom handler with this Condition.
The supplied functor will be called when this Condition is triggered and either the dds::core::cond::Condition::dispatch() is called or the dds::core::cond::WaitSet::dispatch() on the WaitSet to which this Condition is attached to.
- Template Parameters
-
| Functor | The functor to be called when the StatusCondition triggers. |
- Returns
- void
- Exceptions
-
◆ is_nil()
template<typename DELEGATE>
Check if the referenced object is nil.
In other words, check if the reference is pointing to a null object.
- Returns
- true if the referenced object is null.
◆ operator!=() [1/2]
template<typename DELEGATE>
Special operator!= used to check if this reference object does not equal the dds::core::null reference.
The non-null-check can be done like this:
if (r != dds::core::null) {
}
- Returns
- true if this reference is not null.
◆ operator!=() [2/2]
template<typename DELEGATE>
template<typename R >
Compares two Reference objects and returns true if they are not equal.
Inequality is based on the referential inequality of the object being pointed to.
- Parameters
-
| ref | the other Reference object |
- Returns
- true when not equal
◆ operator->() [1/2]
template<typename DELEGATE>
The operator->() is provided to be able to directly invoke functions on the delegate.
The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:
my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();
- Returns
- a reference to delegate.
◆ operator->() [2/2]
template<typename DELEGATE>
The operator->() is provided to be able to directly invoke functions on the delegate.
The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:
my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();
- Returns
- a reference to delegate.
◆ operator==() [1/2]
template<typename DELEGATE>
Special operator== used to check if this reference object equals the dds::core::null reference.
The null-check can be done like this:
if (r == dds::core::null) {
}
- Returns
- true if this reference is null.
◆ operator==() [2/2]
template<typename DELEGATE>
template<typename R >
Compares two Reference objects and returns true if they are equal.
Equality is based on the referential equality of the object being pointed.
- Parameters
-
| ref | the other Reference object |
- Returns
- true when equal
◆ reset_handler()
| void dds::core::cond::Condition::reset_handler |
( |
| ) |
|
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inherited |
Resets the handler for this Condition.
After the invocation of this function no handler will be registered with this Condition.
- Returns
- void
- Exceptions
-
◆ state_filter()
◆ trigger_value()
| bool dds::core::cond::Condition::trigger_value |
( |
| ) |
const |
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inherited |
This operation retrieves the trigger_value of the Condition.
A Condition has a trigger_value that can be TRUE or FALSE and is set by the Data Distribution Service (except a GuardCondition). This operation returns the trigger_value of the Condition.
- Returns
- bool The boolean value to which the Condition is set.
- Exceptions
-
The documentation for this class was generated from the following file:
1.8.16