mirror of
https://github.com/wqking/eventpp.git
synced 2024-12-27 16:41:11 +08:00
126 lines
3.6 KiB
Markdown
126 lines
3.6 KiB
Markdown
# Class CounterRemover reference
|
|
|
|
## Description
|
|
|
|
CounterRemover is a utility class that automatically removes listeners after the listeners are triggered for certain times.
|
|
CounterRemover is a pure functional class. After the member functions in CounterRemover are invoked, the CounterRemover object can be destroyed safely.
|
|
|
|
<a name="apis"></a>
|
|
## API reference
|
|
|
|
### Header
|
|
|
|
eventpp/utilities/counterremover.h
|
|
|
|
### Template parameters
|
|
|
|
```c++
|
|
template <typename DispatcherType>
|
|
class CounterRemover;
|
|
```
|
|
|
|
`DispatcherType` can be CallbackList, EventDispatcher, or EventQueue.
|
|
|
|
### Member functions
|
|
|
|
```c++
|
|
explicit CounterRemover(DispatcherType & dispatcher);
|
|
```
|
|
|
|
Constructs an instance of CounterRemover.
|
|
|
|
**Member functions for EventDispatcher and EventQueue**
|
|
```c++
|
|
typename DispatcherType::Handle appendListener(
|
|
const typename DispatcherType::Event & event,
|
|
const typename DispatcherType::Callback & listener,
|
|
const int triggerCount = 1
|
|
);
|
|
|
|
typename DispatcherType::Handle prependListener(
|
|
const typename DispatcherType::Event & event,
|
|
const typename DispatcherType::Callback & listener,
|
|
const int triggerCount = 1
|
|
);
|
|
|
|
typename DispatcherType::Handle insertListener(
|
|
const typename DispatcherType::Event & event,
|
|
const typename DispatcherType::Callback & listener,
|
|
const typename DispatcherType::Handle & before,
|
|
const int triggerCount = 1
|
|
);
|
|
```
|
|
|
|
**Member functions for CallbackList**
|
|
```c++
|
|
typename CallbackListType::Handle append(
|
|
const typename CallbackListType::Callback & listener,
|
|
const int triggerCount = 1
|
|
);
|
|
|
|
typename CallbackListType::Handle prepend(
|
|
const typename CallbackListType::Callback & listener,
|
|
const int triggerCount = 1
|
|
);
|
|
|
|
typename CallbackListType::Handle insert(
|
|
const typename CallbackListType::Callback & listener,
|
|
const typename CallbackListType::Handle & before,
|
|
const int triggerCount = 1
|
|
);
|
|
```
|
|
|
|
The member functions have the same names with the corresponding underlying class (CallbackList, EventDispatcher, or EventQueue), and also have the same parameters except there is one more parameter, `triggerCount`. `triggerCount` is decreased by one on each trigger, and when `triggerCount` is zero or negative, the listener will be removed.
|
|
The default value of `triggerCount` is 1, that means the listener is removed after the first trigger, which is one shot listener.
|
|
|
|
### Free functions
|
|
|
|
```c++
|
|
template <typename DispatcherType>
|
|
CounterRemover<DispatcherType> counterRemover(DispatcherType & dispatcher);
|
|
```
|
|
|
|
Since CounterRemover takes one template parameter and it's verbose to instantiate its instance, the function `counterRemover` is used to construct an instance of CounterRemover via the deduced argument.
|
|
|
|
### Same code
|
|
|
|
```c++
|
|
#include "eventpp/utilities/counterremover.h"
|
|
#include "eventpp/eventdispatcher.h"
|
|
|
|
eventpp::EventDispatcher<int, void ()> dispatcher;
|
|
constexpr int event = 3;
|
|
|
|
dispatcher.appendListener(event, []() {
|
|
// listener A
|
|
});
|
|
|
|
// Note the CounterRemover instance returned by counterRemover is invoked
|
|
// prependListener and destroyed immediately.
|
|
eventpp::counterRemover(dispatcher).prependListener(event, []() {
|
|
// listener B
|
|
});
|
|
auto handle = eventpp::counterRemover(dispatcher).appendListener(event, []() {
|
|
// listener C
|
|
}, 2);
|
|
eventpp::counterRemover(dispatcher).insertListener(event, []() {
|
|
// listener D
|
|
}, handle, 3);
|
|
|
|
dispatcher.dispatch(event);
|
|
// All listeners were triggered.
|
|
// Listener B was removed.
|
|
|
|
dispatcher.dispatch(event);
|
|
// Listeners A, C, D were triggered.
|
|
// Listener C was removed.
|
|
|
|
dispatcher.dispatch(event);
|
|
// Listeners A, D were triggered.
|
|
// Listener D was removed.
|
|
|
|
dispatcher.dispatch(event);
|
|
// Listeners A was triggered.
|
|
|
|
```
|