Multiple doc templates in a SDI

Dan Green -- s3036076@pompeii.mpce.mq.edu.au
Monday, September 02, 1996

Environment: VC++ 4.0 / NT 3.51

I have a SDI app using CFormView as the view type.  It has a
corresponding CDocument derived class (CFooDoc).
To add a twist, I require an extra document (CIndexDoc) that will handle
an index relating to the information contained in CFooDoc.
Without going into details, trust me when I say that CIndexDoc must be
self-contained and serialized to a DIFFERENT file than CFooDoc.
OK, to facilitate this I added a public CSingleDocTemplate* member to
the CWinApp derived class (CFooApp) and instantiate it in
CFooApp::InitInstance().  (I purposely do not use AddDocTemplate() as I
don't want the application to maintain it.)
So far so good (I hope).
What has me concerned, is that to reference, for example, the public
function CIndexDoc::Kaboom() I use:
   ((CFooDoc*)(((CFooApp*)AfxGetApp())->pIndexDoc))->Kaboom();
Sheesh!  If that ain't the ugliest thing you've ever seen?!
Please show me the sensible version which MUST exist.

Thanks for wading through the swamp with me,
Dan.

---
Daniel Green
s3036076@pompeii.mpce.mq.edu.au

---

Roger Onslow -- Roger_Onslow@compsys.com.au
Tuesday, September 03, 1996

[Mini-digest: 2 responses]

>   ((CFooDoc*)(((CFooApp*)AfxGetApp())->pIndexDoc))->Kaboom();
>Sheesh!  If that ain't the ugliest thing you've ever seen?!
Sure is -- mind you, you haven't seen me first thing in the morning :-)

Lets break it into bits:
 ((CFooApp*)AfxGetApp())
yuk, lets define a static member function of your app like this
 class CFooApp : public CWinApp {
  ...
  static CFooApp* TheApp () { return static_cast(::AfxGetApp()); }
  ...
 };
NOTE: I used C++ static_cast operator because these new operators help document 
why you are casting and help avoid mis-casts -- if you are using an easrlier 
version of VC++, just use an old-fashioned cast.

OK, now lets take care of getting at the index doc
 class CFooApp : public CWinApp {
  ...
  CFooDoc* GetIndexDoc() { return pIndexDoc; }
  ...
 };
NOTE: I would have used m_pIndexDoc as per MFC conventions, but that's just me 
(and MS!) :-)
Of course, you would then make pIndexDoc private -- shouldn't flash your 
internal bits to the whole world!!

Now you can do
 (CFooApp::TheApp()->GetIndexDoc())->Kaboom()
which is not *quite* so ugly.
Of couse, you could write:
 class CFooApp : public CWinApp {
  ...
  void IndexDocKaboom () { GetIndexDoc()->Kaboom(); }
  ...
 };
And then just do:
 CFooApp::TheApp()->IndexDocKaboom()
which is almost nice!!

>Thanks for wading through the swamp with me,
What out for the leeches !!

Roger Onslow
RogerO@compsys.com.au

[ Homer: "Operator, Give me the number for 911" -- it's MFC-L :-)]
-----From: David Wruck 

Have you considered writing helper functions that perform the casts for =
you? =20

For example, you could write a "CFooApp* GetFooApp()" function that =
calls AfxGetApp() and performs the cast from CWinApp* to CFooApp*.  You =
could then add a member function to CFooApp called "CIndexDoc* =
GetIndexDoc()" that returns the pointer to your document.

Calls would then look like this: GetFooApp()->GetIndexDoc()->Kaboom();

To improve on this, you can even dereference the pointers to return a =
reference instead.  This will allow you to use "." notation instead of =
pointer "->" notation.

I hope this helps.

---

rkumar@mail.cswl.com
Thursday, September 05, 1996

Environment: VC++ 4.0 / NT 3.51
     
I have a SDI app using CFormView as the view type.  It has a 
corresponding CDocument derived class (CFooDoc).
To add a twist, I require an extra document (CIndexDoc) that will handle 
an index relating to the information contained in CFooDoc.
Without going into details, trust me when I say that CIndexDoc must be 
self-contained and serialized to a DIFFERENT file than CFooDoc.
OK, to facilitate this I added a public CSingleDocTemplate* member to 
the CWinApp derived class (CFooApp) and instantiate it in 
CFooApp::InitInstance().  (I purposely do not use AddDocTemplate() as I 
don't want the application to maintain it.)
So far so good (I hope).
What has me concerned, is that to reference, for example, the public 
function CIndexDoc::Kaboom() I use:
   ((CFooDoc*)(((CFooApp*)AfxGetApp())->pIndexDoc))->Kaboom();
Sheesh!  If that ain't the ugliest thing you've ever seen?! 
Please show me the sensible version which MUST exist.
     
Thanks for wading through the swamp with me, 
Dan.
     
---
Daniel Green
s3036076@pompeii.mpce.mq.edu.au


Other way to have nice thing do the following:-


Add a public member function say GetIndexDocument() to your application class, 
which will return pointer to IndexDoc. This is other (sensible) way of doing 
what U have done.

Look like this.,

CFooDoc* CFooApp::GetIndexDocument()
{
    return ((CFooApp*)AfxGetApp())->pIndexDoc;
}

---

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