DOC:CDocTemplate::CreateNewFrame() Won't Make New CDocument (121321)


The information in this article applies to:

  • The Microsoft Foundation Classes (MFC), when used with:
    • Microsoft Visual C++ for Windows, 16-bit edition 1.0
    • Microsoft Visual C++ for Windows, 16-bit edition 1.5
    • Microsoft Visual C++ for Windows, 16-bit edition 1.51
    • Microsoft Visual C++, 32-bit Editions 1.0
    • Microsoft Visual C++, 32-bit Editions 2.0
This article was previously published under Q121321

SUMMARY

The Help File documentation for CDocTemplate::CreateNewFrame() says: 
   If the pDoc parameter is NULL, a new document will be created
   if the appropriate runtime class is available; otherwise the
   new view will be associated with the ...
This is not correct. Calling CreateNewFrame() with a NULL pDoc parameter actually results in an assertion failure on the pDoc pointer and a TRACE() statement in your output or debug window stating the following:
ASSERT_VALID fails with NULL pointer.
The reason for this is that CreateNewFrame() is not the appropriate function to call when you don't have a pre-constructed CDocument-derived object. The function to call is CMultiDocTemplate's or CSingleDocTemplate's OpenDocumentFile(). The OpenDocumentFile() function creates a new CDocument object by using CreateNewDocument().

MORE INFORMATION

CMultiDocTemplate:: and CSingleDocTemplate::OpenDocumentFile() both create a new document if the pointer argument passed to them is NULL. To get a pointer to the appropriate document template that you can use when calling OpenDocumentFile(), please see the following article in the Microsoft Knowledge Base:

106455 Acquiring a List of All CDocument Objects

This article contains sample code you can use to traverse the list of available document templates.

This problem was fixed in Microsoft Visual C++, 32-bit Edition, version 4.0.
Modification Type:MajorLast Reviewed:12/1/2003
Keywords:kbdocfix KB121321
©2003 Microsoft Corporation. All rights reserved.