When to kill an object
 

Hi there,

I have a general question on what's best practise for killing redundant
objects.

For example, I've been using 'Set objRng = Nothing' at the end of various
procedures on the assumption that this clears them from memory.
So.............

a) Is that what happens?

b) Are variables/objects cleared when a workbook is closed, the application,
or on re-boot the whole PC!?

Thanks in advance

John

When to kill an object
 

Setting an object to nothing when you are done with it is never a bad idea.
That being said VB is (if you believe the glossy brochure) self cleaning and
will destroy any objects when they are done. That is to say when the sub
procedure ends. All of this assumes that the objects are declared locally and
not globally. Local variables ar stored on the stack which is destroyed when
procedures end, where as global variables are stored on the heap which exists
for so long as the project is active.

I myself don't specifically clean up locally declared workbook, worksheet or
range objects (unless they are instantiated multiple times in a loop). My
thought are what is the worst that can happen if they don't get cleaned up.
How much memory is being lost as a result. In they typical application not
very much.

The one exception to this is if I declare objects which are links to other
programs such as ADO record sets or instantiations of other programs like
Word. Then I am always very careful to clean up after myself.
--
HTH...

Jim Thomlinson


"John" wrote:

Hi there,

I have a general question on what's best practise for killing redundant
objects.

For example, I've been using 'Set objRng = Nothing' at the end of various
procedures on the assumption that this clears them from memory.
So.............

a) Is that what happens?

b) Are variables/objects cleared when a workbook is closed, the application,
or on re-boot the whole PC!?

Thanks in advance

John

When to kill an object
 

Jim,

That's great. Thanks very much for your expertise. I shall rest easy on my
"locals" and take more care with cross app code as you suggest.

Are you able to point me towards a good background on memory management?
I've heard of heap and stack, but don't really understand where they sit in
the big scheme of things and, perhaps I ought to.......bedtime reading
perhaps!

Anyway thanks very much for your help.

Best regards

John


"Jim Thomlinson" wrote in message
...
Setting an object to nothing when you are done with it is never a bad
idea.
That being said VB is (if you believe the glossy brochure) self cleaning
and
will destroy any objects when they are done. That is to say when the sub
procedure ends. All of this assumes that the objects are declared locally
and
not globally. Local variables ar stored on the stack which is destroyed
when
procedures end, where as global variables are stored on the heap which
exists
for so long as the project is active.

I myself don't specifically clean up locally declared workbook, worksheet
or
range objects (unless they are instantiated multiple times in a loop). My
thought are what is the worst that can happen if they don't get cleaned
up.
How much memory is being lost as a result. In they typical application not
very much.

The one exception to this is if I declare objects which are links to other
programs such as ADO record sets or instantiations of other programs like
Word. Then I am always very careful to clean up after myself.
--
HTH...

Jim Thomlinson


"John" wrote:

Hi there,

I have a general question on what's best practise for killing redundant
objects.

For example, I've been using 'Set objRng = Nothing' at the end of various
procedures on the assumption that this clears them from memory.
So.............

a) Is that what happens?

b) Are variables/objects cleared when a workbook is closed, the
application,
or on re-boot the whole PC!?

Thanks in advance

John

When to kill an object
 

I took a couple of courses in C and learned more about memory than you can
shake a stick at. That of course does not help you. As for books... Not too
sure.
--
HTH...

Jim Thomlinson


"John" wrote:

Jim,

That's great. Thanks very much for your expertise. I shall rest easy on my
"locals" and take more care with cross app code as you suggest.

Are you able to point me towards a good background on memory management?
I've heard of heap and stack, but don't really understand where they sit in
the big scheme of things and, perhaps I ought to.......bedtime reading
perhaps!

Anyway thanks very much for your help.

Best regards

John


"Jim Thomlinson" wrote in message
...
Setting an object to nothing when you are done with it is never a bad
idea.
That being said VB is (if you believe the glossy brochure) self cleaning
and
will destroy any objects when they are done. That is to say when the sub
procedure ends. All of this assumes that the objects are declared locally
and
not globally. Local variables ar stored on the stack which is destroyed
when
procedures end, where as global variables are stored on the heap which
exists
for so long as the project is active.

I myself don't specifically clean up locally declared workbook, worksheet
or
range objects (unless they are instantiated multiple times in a loop). My
thought are what is the worst that can happen if they don't get cleaned
up.
How much memory is being lost as a result. In they typical application not
very much.

The one exception to this is if I declare objects which are links to other
programs such as ADO record sets or instantiations of other programs like
Word. Then I am always very careful to clean up after myself.
--
HTH...

Jim Thomlinson


"John" wrote:

Hi there,

I have a general question on what's best practise for killing redundant
objects.

For example, I've been using 'Set objRng = Nothing' at the end of various
procedures on the assumption that this clears them from memory.
So.............

a) Is that what happens?

b) Are variables/objects cleared when a workbook is closed, the
application,
or on re-boot the whole PC!?

Thanks in advance

John

When to kill an object
 

Well maybe a "book" is more than I need at the moment, but thanks anyway
Jim.

I've since come across a nice article (for anyone who's interested) which
explains the "heap" and "stack" parts at a level I'm able to understand!
It's really for VB.Net but I assume this principles are the same:

http://www.devcity.net/Articles/79/1...cal_oop_1.aspx

Best regards

John


"Jim Thomlinson" wrote in message
...
I took a couple of courses in C and learned more about memory than you can
shake a stick at. That of course does not help you. As for books... Not
too
sure.
--
HTH...

Jim Thomlinson


"John" wrote:

Jim,

That's great. Thanks very much for your expertise. I shall rest easy on
my
"locals" and take more care with cross app code as you suggest.

Are you able to point me towards a good background on memory management?
I've heard of heap and stack, but don't really understand where they sit
in
the big scheme of things and, perhaps I ought to.......bedtime reading
perhaps!

Anyway thanks very much for your help.

Best regards

John


"Jim Thomlinson" wrote in message
...
Setting an object to nothing when you are done with it is never a bad
idea.
That being said VB is (if you believe the glossy brochure) self
cleaning
and
will destroy any objects when they are done. That is to say when the
sub
procedure ends. All of this assumes that the objects are declared
locally
and
not globally. Local variables ar stored on the stack which is destroyed
when
procedures end, where as global variables are stored on the heap which
exists
for so long as the project is active.

I myself don't specifically clean up locally declared workbook,
worksheet
or
range objects (unless they are instantiated multiple times in a loop).
My
thought are what is the worst that can happen if they don't get cleaned
up.
How much memory is being lost as a result. In they typical application
not
very much.

The one exception to this is if I declare objects which are links to
other
programs such as ADO record sets or instantiations of other programs
like
Word. Then I am always very careful to clean up after myself.
--
HTH...

Jim Thomlinson


"John" wrote:

Hi there,

I have a general question on what's best practise for killing
redundant
objects.

For example, I've been using 'Set objRng = Nothing' at the end of
various
procedures on the assumption that this clears them from memory.
So.............

a) Is that what happens?

b) Are variables/objects cleared when a workbook is closed, the
application,
or on re-boot the whole PC!?

Thanks in advance

John