Class CAsyncCallBack

class CAsyncCallBack : public CAsyncOneShot;

Description

An active object that performs its processing through an associated call back function, and which is only performed once.

Derivation

• CBase - Base class for all classes to be instantiated on the heap.

• CActive - The core class of the active object abstraction.

• CAsyncOneShot - An active object that performs processing that is only performed once.

• CAsyncCallBack - ...

Members

Defined in CAsyncCallBack:

• CAsyncCallBack(TInt)Constructor taking a priority value.
• CAsyncCallBack(const TCallBack &,TInt)Constructor taking a priority value and a callback.
• CallBack()Queues this active object to be run, if it is not already queued.
• RunL()Calls the callback function.
• Set(const TCallBack &)Sets the call back.
• iCallBackThe callback object that encapsulates the callback function.
• ~CAsyncCallBack()Destructor.

Inherited from CActive:

• CActive(TInt)Constructs the active object with the specified priority.
• Cancel()Cancels the wait for completion of an outstanding request.
• Deque()Removes the active object from the active scheduler's list of active objects.
• EPriorityHighA priority higher than EPriorityUserInput.
• EPriorityIdleA low priority, useful for active objects representing background processing.
• EPriorityLowA priority higher than EPriorityIdle but lower than EPriorityStandard.
• EPriorityStandardMost active objects will have this priority.
• EPriorityUserInputA priority higher than EPriorityStandard; useful for active objects handling use...
• Extension_(TUint,TAny *&,TAny *)Extension function
• IsActive()constDetermines whether the active object has a request outstanding.
• IsAdded()constDetermines whether the active object has been added to the active scheduler's li...
• Priority()constGets the priority of the active object.
• RunError(TInt)Handles a leave occurring in the request completion event handler CActive::RunL(...
• SetActive()Indicates that the active object has issued a request and that it is now outstan...
• SetPriority(TInt)Sets the priority of the active object.
• TPriorityDefines standard priorities for active objects.
• iStatusThe request status associated with an asynchronous request.

Inherited from CAsyncOneShot:

• CAsyncOneShot(TInt)Constructor taking a priority value.
• Call()Queues this active object to be run once.
• DoCancel()Implements cancellation of an outstanding request.
• Thread()Gets a handle to the current thread.

Inherited from CBase:

• Delete(CBase *)Deletes the specified object.
• operator new(TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TAny *)Initialises the object to binary zeroes.
• operator new(TUint,TLeave)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TLeave,TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TUint)Allocates the object from the heap and then initialises its contents to binary z...

IMPORT_C CAsyncCallBack(TInt aPriority);

Description

Constructor taking a priority value.

Specifically, the constructor sets this active object's priority value through a call to the base class constructor in its ctor list.

No call back is set, which means that it must be set subsequently through a call to the CAsyncCallBack::Set(const TCallBack &) function.

Parameters

TInt aPriority The active object priority value. CActive::TPriority defines a standard set of priorities.

See also:

• CAsyncCallBack::Set(const TCallBack &)Sets the call back.

IMPORT_C CAsyncCallBack(const TCallBack &aCallBack, TInt aPriority);

Description

Constructor taking a priority value and a callback.

Specifically, the constructor:

1. sets this active object's priority value through a call to the base class constructor in its ctor list

2. sets the callback; the function encapsulated by the callback is called when this active object is scheduled to run.

Parameters

const TCallBack &aCallBack A reference to a callback object encapsulating a function which is called when this active object is ready to run. The constructor takes a copy of this callback object, which means that it can be safely discarded after construction. TInt aPriority The active object priority value.

IMPORT_C virtual ~CAsyncCallBack();

Description

Destructor.

IMPORT_C void Set(const TCallBack &aCallBack);

Description

Sets the call back.

Parameters

const TCallBack &aCallBack A reference to a callback object encapsulating a function which is called when this active object is ready to run.

Panic codes

E32USER-CBase 1 if the active object is currently active.

IMPORT_C void CallBack();

Description

Queues this active object to be run, if it is not already queued.

protected: virtual void RunL();

Description

Calls the callback function.

See also:

• TCallBack::CallBack()constCalls the callback function.

protected: TCallBack iCallBack;

Description

The callback object that encapsulates the callback function.