Remarks

Contains information about how a collection is about to change.

Template Parameters

T	Type of element in the collection

In contrast to NotifyCollectionChangedEventArgs, this object represents changes that are about to happen, not changes that have happened already.

See also: INotifyListChanging<T>

Public fields
ListChangeInfo(IListSource< T > collection, NotifyCollectionChangedAction action, int index, int sizeChange, IListSource< T > newItems=null) readonly NotifyCollectionChangedAction	Action
	This contructor is meant for ListChanging events only (not ListChanged). It computes the OldItems property automatically, on-demand, if the user gets it. More...

readonly int	Index
	Gets the index at which the add, remove, or change operation starts. If the collection is not a list (e.g. it is a dictionary), this should be Int32.MinValue. More...

int	NewStartingIndex => Index
	Returns Index. Exists for compatibility with NotifyCollectionChangedEventArgs. More...

int	OldStartingIndex => Index
	Returns Index. Exists for compatibility with NotifyCollectionChangedEventArgs. More...

readonly int	SizeChange
	Gets the amount by which the collection size changes. When items are being added, this is positive, and when items are being removed, this is negative. This is 0 when existing items are only being replaced. More...

IListSource< T >	_collection

IListSource< T >	NewItems => _newItems
	Represents either new item(s) that are being added to the collection, or item(s) that are replacing existing item(s) in the collection. When items are being removed from an indexed list, this member is either null or empty. More...

IListSource< T >	OldItems => _oldItems ?? ComputeOldItems()
	This member may provide a list of old items that are being removed or replaced in the collection. It may be null when items are being added. More...

Public Member Functions
	ListChangeInfo (NotifyCollectionChangedAction action, int index, int sizeChange, IListSource< T > newItems)
	Initializes the members of ListChangeInfo<T>. More...

	ListChangeInfo (NotifyCollectionChangedAction action, int index, int sizeChange, IListSource< T > newItems, IListSource< T > oldItems)

Constructor & Destructor Documentation

◆ ListChangeInfo()

Loyc.Collections.ListChangeInfo< T >.ListChangeInfo	(	NotifyCollectionChangedAction	action,
		int	index,
		int	sizeChange,
		IListSource< T >	newItems
	)

inline

Initializes the members of ListChangeInfo<T>.

Member Data Documentation

◆ Action

ListChangeInfo (IListSource<T> collection, NotifyCollectionChangedAction action, int index, int sizeChange, IListSource<T> newItems = null) readonly NotifyCollectionChangedAction Loyc.Collections.ListChangeInfo< T >.Action

This contructor is meant for ListChanging events only (not ListChanged). It computes the OldItems property automatically, on-demand, if the user gets it.

Parameters

collection	The list that is about to change.
action	Should be Remove, Reset or Replace.

Gets a value that indicates the type of change being made to the collection.

◆ Index

readonly int Loyc.Collections.ListChangeInfo< T >.Index

Gets the index at which the add, remove, or change operation starts. If the collection is not a list (e.g. it is a dictionary), this should be Int32.MinValue.

◆ NewItems

IListSource<T> Loyc.Collections.ListChangeInfo< T >.NewItems => _newItems

Represents either new item(s) that are being added to the collection, or item(s) that are replacing existing item(s) in the collection. When items are being removed from an indexed list, this member is either null or empty.

In a ListChanged event, the collection returned from this property could be a slice that will be invalid after the event is over. Avoid storing it without making a copy.

◆ NewStartingIndex

int Loyc.Collections.ListChangeInfo< T >.NewStartingIndex => Index

Returns Index. Exists for compatibility with NotifyCollectionChangedEventArgs.

◆ OldItems

IListSource<T> Loyc.Collections.ListChangeInfo< T >.OldItems => _oldItems ?? ComputeOldItems()

This member may provide a list of old items that are being removed or replaced in the collection. It may be null when items are being added.

In a ListChanging event, the collection returned from this property may be empty if the list is being sorted in-place, since it is not known what the new list will be. In any case, this property is typically a slice and therefore is not valid after the event is over; avoid storing it without making a copy.

◆ OldStartingIndex

int Loyc.Collections.ListChangeInfo< T >.OldStartingIndex => Index