CreateBindCtx

This function supplies a pointer to an implementation of IBindCtx, an object that stores information about a particular moniker-binding operation.

At a Glance

Syntax

WINOLEAPI CreateBindCtx ( DWORD reserved, LPBC FAR * ppbc);

Parameters

reserved

[in] Reserved for future use; set to zero.

ppbc

[out] Address of IBindCtx* pointer variable that receives the interface pointer to the new bind context object. When the function is successful, the caller is responsible for calling IUnknown::Release on the bind context. A NULL value for the bind context indicates that an error occurred.

Return Values

S_OK indicates that the bind context was allocated and initialized successfully. The standard return value E_OUTOFMEMORY is also supported.

Remarks

CreateBindCtx is most commonly used in the process of binding a moniker (locating and getting a pointer to an interface by identifying it through a moniker), as in the following steps:

1. Get a pointer to a bind context by calling the CreateBindCtx function.
   
   
2. Call the IMoniker::BindToObject method on the moniker, retrieving an interface pointer to the object to which the moniker refers.
   
   
3. Release the bind context.
   
   
4. Use the interface pointer.
   
   
5. Release the interface pointer.

The following code example shows these steps.

// pMnk is an IMoniker * that points to a previously acquired moniker 
IFoo *pFoo; 
IBindCtx *pbc; 
 
CreateBindCtx( 0, &pbc ); 
pMnk->BindToObject( pbc, NULL, IID_IFoo, &pFoo ); 
pbc->Release(); 
// pFoo now points to the object; safe to use pFoo 
pFoo->Release(); 
 

Bind contexts are also used in other methods of the IMoniker interface besides IMoniker::BindToObject.

A bind context retains references to the objects that are bound during the binding operation, causing the bound objects to remain active (keeping the object's server running) until the bind context is released. Reusing a bind context when subsequent operations bind to the same object can improve performance. You should, however, release the bind context as soon as possible, because you could be keeping the objects activated unnecessarily.

A bind context contains a BIND_OPTS structure, which contains parameters that apply to all steps in a binding operation. When you create a bind context using CreateBindCtx, the fields of the BIND_OPTS structure are initialized to the following values:

cbStruct = sizeof(BIND_OPTS) 
grfFlags = 0 
grfMode = STGM_READWRITE 
dwTickCountDeadline = 0. 
 

You can call the IBindCtx::SetBindOptions method to modify these default values.