Q121321: DOC:CDocTemplate::CreateNewFrame() Won’t Make New CDocument

Article: Q121321
Product(s): Microsoft C Compiler
Version(s): 1.00 1.50 1.51 | 1.00 2.00
Operating System(s): 
Keyword(s): kbdocfix
Last Modified: 25-JUL-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), included with:
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0 
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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:

  Q106455 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.

Additional query words: pDoc ASSERT_VALID OpenDocumentFile 1.00 1.50 2.00 2.10 2.50 2.51 3.00 4.00

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Keywords          : kbdocfix 
Technology        : kbAudDeveloper kbMFC
Version           : 1.00 1.50 1.51 | 1.00 2.00

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