EnumerableComCollection<TComEnumerator, TEnumerated> Class

Article
07/12/2014

Provides a generic base class for types that provide an IEnumerable wrapper around COM-style IEnumXXX interfaces.

Inheritance Hierarchy

System.Object
  Microsoft.VisualStudio.Shell.EnumerableComCollection<TComEnumerator, TEnumerated>
    Microsoft.Internal.VisualStudio.PlatformUI.EnumerablePropertiesCollection
    Microsoft.Internal.VisualStudio.PlatformUI.EnumerableVerbsCollection
    Microsoft.VisualStudio.Shell.EnumerableHierarchiesCollection

Namespace: Microsoft.VisualStudio.Shell
Assembly: Microsoft.VisualStudio.Shell.11.0 (in Microsoft.VisualStudio.Shell.11.0.dll)

Syntax

'Declaration
Public MustInherit Class EnumerableComCollection(Of TComEnumerator, TEnumerated) _
    Implements IEnumerable(Of TEnumerated), IEnumerable,  _
    IComEnumeratorRelay(Of TComEnumerator, TEnumerated)

public abstract class EnumerableComCollection<TComEnumerator, TEnumerated> : IEnumerable<TEnumerated>, 
    IEnumerable, IComEnumeratorRelay<TComEnumerator, TEnumerated>

generic<typename TComEnumerator, typename TEnumerated>
public ref class EnumerableComCollection abstract : IEnumerable<TEnumerated>, 
    IEnumerable, IComEnumeratorRelay<TComEnumerator, TEnumerated>

[<AbstractClass>]
type EnumerableComCollection<'TComEnumerator, 'TEnumerated> =  
    class 
        interface IEnumerable<'TEnumerated>
        interface IEnumerable 
        interface IComEnumeratorRelay<'TComEnumerator, 'TEnumerated>
    end

JScript does not support generic types or methods.

Type Parameters

TComEnumerator
A COM enumerator type (e.g. IEnumString).

TEnumerated
The type of the enumerator.

The EnumerableComCollection<TComEnumerator, TEnumerated> type exposes the following members.

Constructors

	Name	Description
	EnumerableComCollection<TComEnumerator, TEnumerated>(TComEnumerator)	Initializes a new instance of EnumerableComCollection<TComEnumerator, TEnumerated> for the provided enumerator.
	EnumerableComCollection<TComEnumerator, TEnumerated>(TComEnumerator, Int32)	Initializes a new instance of EnumerableComCollection<TComEnumerator, TEnumerated> for the provided enumerator and cache size.

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Methods

	Name	Description
	Clone	Clones the item with the specified enumerator .
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetEnumerator	Gets the enumerator.
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	NextItems	Gets the specified number of items.
	Reset	Resets the counter of the collection.
	Skip	Skips the specified number of items.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Fields

	Name	Description
	DefaultCacheSize	The default cache size.

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Explicit Interface Implementations

	Name	Description
	IEnumerable.GetEnumerator	Gets the enumerator.

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Remarks

Classes that derive from this class change a COM-style IEnumXXX interface into a form that can be processed by a foreach statement. You must derive a separate class from this base class due to the way C# generics are defined.

This class must call methods on the COM enumerator that it wraps (Next(), Skip(), etc.), but generic types can access properties and methods only on the parameterized types that are specified in the their constraints. For example, you can call TComEnumerator.Next() only if you specify a constraint on TComEnumerator that tells the compiler that the type implements Next().

COM IEnumXXX interfaces are strongly typed. In other words, the IEnumXXX.Next() method returns an array of XXX objects. Because these interfaces do not have a common base interface, you cannot place a constraint on TComEnumerator directly. You can solve this problem by implementing the IComEnumeratorRelay<TComEnumerator, TEnumerated> interface along with the EnumerableComCollection<TComEnumerator, TEnumerated> interface. Doing so allows the generic type to call into the COM enumerator without having to place a constraint on TComEnumerator.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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