I think there is quite a confusion over the usage of "On" as prefix of a C# method.
In MSDN article "Handling and Raising Event" https://msdn.microsoft.com/en-us/library/edzehd2t(v=vs.110).aspx it says,
Typically, to raise an event, you add a method that is marked as
protected and virtual (in C#) or Protected and Overridable (in Visual
Basic). Name this method OnEventName; for example, OnDataReceived. The
method should take one parameter that specifies an event data object.
You provide this method to enable derived classes to override the
logic for raising the event. A derived class should always call the
OnEventName method of the base class to ensure that registered
delegates receive the event.
indicating the On... method is to raise an event. However, in many coding samples, even some provided by Microsoft, we can see event the On method used as event handler, like on in here https://msdn.microsoft.com/en-us/windows/uwp/gaming/tutorial--adding-move-look-controls-to-your-directx-game?f=255&MSPPError=-2147217396
First, let's populate the mouse and touch pointer event handlers. In
the first event handler, OnPointerPressed(), we get the x-y
coordinates of the pointer from the CoreWindow that manages our
display when the user clicks the mouse or touches the screen in the
look controller region.
_In_ CoreWindow^ sender,
_In_ PointerEventArgs^ args)
// Get the current pointer position.
uint32 pointerID = args->CurrentPoint->PointerId;
DirectX::XMFLOAT2 position = DirectX::XMFLOAT2( args->CurrentPoint->Position.X, args->CurrentPoint->Position.Y );
auto device = args->CurrentPoint->PointerDevice;
auto deviceType = device->PointerDeviceType;
if ( deviceType == PointerDeviceType::Mouse )
// Action, Jump, or Fire
// Check if this pointer is in the move control.
// Change the values to percentages of the preferred screen resolution.
// You can set the x value to <preferred resolution> * <percentage of width>
// for example, ( position.x < (screenResolution.x * 0.15) ).
if (( position.x < 300 && position.y > 380 ) && ( deviceType != PointerDeviceType::Mouse ))
if ( !m_moveInUse ) // if no pointer is in this control yet
// Process a DPad touch down event.
m_moveFirstDown = position; // Save the location of the initial contact.
m_movePointerPosition = position;
m_movePointerID = pointerID; // Store the id of the pointer using this control.
m_moveInUse = TRUE;
else // This pointer must be in the look control.
if ( !m_lookInUse ) // If no pointer is in this control yet...
m_lookLastPoint = position; // save the point for later move
m_lookPointerID = args->CurrentPoint->PointerId; // store the id of pointer using this control
m_lookLastDelta.x = m_lookLastDelta.y = 0; // these are for smoothing
m_lookInUse = TRUE;
My questions being:
- Is there indeed such ambiguity over the usage of "On" prefix or is it just my misunderstanding? Do people really use "On" in both raising and handling event methods?
- What is the standard style of implementing the method raising and handling event? And what are the popular styles? What is the style that you suggest?