Is Powerpoint still a single instance app?

When I want to let go of my PowerPoint instance in c++ I just call the
Release member. I don't do a quit. I start it up by doing a CreateInstance
of PowerPoint. Prior to 2002 there seemed to be a problem with reference
counting because my predecessor had commented out the code to do the release
with a notation about having trouble restarting another instance. I
implemented PowerPoint 2002 and put the release code back in and it worked
as expected.

"Steve Rindsberg" wrote in message
...
It appears t hat it ids NOT necessary to Quit a New instance of PPT
created
by code, except in one circumstance I will describe below. If one just
sets
the app object = Nothing and exits the code, the right thing happens in
all
but 1 circumstance.

2 perhaps. Instances started by code may not go away when you set the
object =
Nothing in PPT97 (and 2000 ... right, Mike?)

The problem occurs only when another use of PPT is started IN CODE and
that
use is not visible. In thiscase, setting the app for the New instance =
nothing also kills the other non-visble instance started by code.

Note that if the other instance started by code is visible, then there's
no
problem. Presentation count can even be 0.

This requires further investigation.

And less hair ... ;-)


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

"Mike M." wrote in message
...
When I want to let go of my PowerPoint instance in c++ I just call the
Release member. I don't do a quit. I start it up by doing a
CreateInstance
of PowerPoint. Prior to 2002 there seemed to be a problem with reference
counting because my predecessor had commented out the code to do the
release
with a notation about having trouble restarting another instance. I
implemented PowerPoint 2002 and put the release code back in and it worked
as expected.

Ayup, I was looking into using the CreateInstance stuff, but I consider that
to be a poor choice.

PPT seems to kill the process as needed.
If there's a bug in any particular PPT version, too bad, attempting to
program around such an issue is not appropriate, as one cannot determine
whether other uses of PPT have started.

Everything I've ever seen states that the ONLY thing one can count on with
reference counts is whether they are 0 or knot.

The bottom line.

The thing that get me sucked into this topic was a decision I made about
two months ago to include, in a VB 6 DLL, code for some Word macros that do
something with PPT via Automation.

In the DLL, for each Word macro, I've got code such as:

Public Sub DoWhateverWithPPT()
Dim appPPT As PowerPoint.Application

'Get existing instance of PowerPoint; otherwise create a new
one
' Powerpoint is a single instance application
On Error Resume Next
Set appPPT = GetObject(, "PowerPoint.Application")
If Err.Number 0 Then
Set appPPT = New PowerPoint.Application
End If
On Error GoTo 0

' He Do whatever with PPT

With appPPT
.ActivePresentation.Close
End With
End Sub

The PowerPoint process is created, and then removed from Task Manager,
wihout my using Quit or = Nothing as soon as the macro completes.

Why?
I expect because appPPT has scope local to the Sub and the reference goes
away when the Sub is exited.
If I were to fiddle around with Quit or = Nothing, then the code would risk
affecting other NON-VISIBLE uses of PPT that may have started AFTER a NEW
instance was created by the code. They may be affected anyway, but there's
nothing I can do about that as I cannot detect the other uses.

In article , Howard Kaikow wrote:
The bottom line.

The thing that get me sucked into this topic was a decision I made about
two months ago to include, in a VB 6 DLL, code for some Word macros that do
something with PPT via Automation.

In the DLL, for each Word macro, I've got code such as:

Public Sub DoWhateverWithPPT()
Dim appPPT As PowerPoint.Application

'Get existing instance of PowerPoint; otherwise create a new
one
' Powerpoint is a single instance application
On Error Resume Next
Set appPPT = GetObject(, "PowerPoint.Application")
If Err.Number 0 Then
Set appPPT = New PowerPoint.Application
End If
On Error GoTo 0

' He Do whatever with PPT

With appPPT
.ActivePresentation.Close
End With
End Sub

The PowerPoint process is created, and then removed from Task Manager,
wihout my using Quit or = Nothing as soon as the macro completes.

Why?
I expect because appPPT has scope local to the Sub and the reference goes
away when the Sub is exited.
If I were to fiddle around with Quit or = Nothing, then the code would risk
affecting other NON-VISIBLE uses of PPT that may have started AFTER a NEW
instance was created by the code. They may be affected anyway, but there's
nothing I can do about that as I cannot detect the other uses.



Not the solution you'd hoped for, but it ends up being a good deal simpler than
what you'd expected it to be. I guess that's A Good Thing?
-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

"Steve Rindsberg" wrote in message
...

Not the solution you'd hoped for, but it ends up being a good deal simpler
than
what you'd expected it to be. I guess that's A Good Thing?

It's not quite the solution I had hoped for.

For example, in a VB 6 class that needs an insrance of Excel or Word, I'd
create that instance and keep it alive for the life of the class.

Not sure I can do that with PPT because there's a chance somebody might
start another use while the class is still running.

I guess that I could keep the object alive for the life of the class, but,
as of now, I feel uncomfortable doing that.

At least I do not have to worry about PPT 97. One of the Word macros will
not run in Word 97, so I'm not going to support the DLL for Word 97.

Not sure I can do that with PPT because there's a chance somebody might
start another use while the class is still running.

Luckily, in most cases that will also create another presentation, so you can
trap a lot of the ugliness based on presentation count. Not perfect, but ...
well. What is?


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

"Steve Rindsberg" wrote in message
...
Not sure I can do that with PPT because there's a chance somebody might
start another use while the class is still running.

Luckily, in most cases that will also create another presentation, so you
can
trap a lot of the ugliness based on presentation count. Not perfect, but
....
well. What is?

Presentation count is not relevant.

The only thing relevant is whether the PPT use is visible,

The following seems to do the deed, where appPPT is a PPT object with scope
of the class, and the following code is included in each procedure that
needs PPT.

appPPT is never Quit nor set = Nothing.

If TypeName(appPPT) "Application" Then
'Get existing instance of PowerPoint; otherwise create a
new one
' Powerpoint is a single instance application
On Error Resume Next
Set appPPT = GetObject(, "PowerPoint.Application")
If Err.Number 0 Then
Set appPPT = New PowerPoint.Application
End If
On Error GoTo 0
End If

The worst case is when the code uses GetObject to set appPPT, but the NEW
instance that was created by somebody else isexited. In that case, the
TypeName test causes my class to reset appPPT and, so on .. ..

In article , Howard Kaikow wrote:
The following seems to do the deed, where appPPT is a PPT object with scope
of the class, and the following code is included in each procedure that
needs PPT.

appPPT is never Quit nor set = Nothing.

If TypeName(appPPT) "Application" Then
'Get existing instance of PowerPoint; otherwise create a
new one
' Powerpoint is a single instance application
On Error Resume Next
Set appPPT = GetObject(, "PowerPoint.Application")
If Err.Number 0 Then
Set appPPT = New PowerPoint.Application
End If
On Error GoTo 0
End If

The worst case is when the code uses GetObject to set appPPT, but the NEW
instance that was created by somebody else isexited. In that case, the
TypeName test causes my class to reset appPPT and, so on .. ..


And, to be certain I have the pieces in order, when the instance you create
here goes out of scope, PPT quits also, but only if your instance is the only
one?

Pretty neat!


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

"Steve Rindsberg" wrote in message
...
And, to be certain I have the pieces in order, when the instance you
create
here goes out of scope, PPT quits also, but only if your instance is the
only
one?

Pretty neat!

The PPT process automatically goes away when there are no more VISIBLE uses
of PPT, and when the NEW instance is Quit.

The implication is that if one never Quits PPT, then one does not adversely
affect others, but others can affect your code if they created the NEW
instance.

It appears that Outlook also works this way, tho i've not tested, so it
appears to be the MSFT "standard" for single instance apps.