Preparing to ...

[Charles H. Sampson]

There are a number of OS X operations that start with a preparation
phase, during which a window is displayed with the phrase "Preparing to
..." Examples are copying a folder, emptying the trash, and making an
archive. Does anyone know why they do this? Why don't they just start
copying the folder, emptying the trash, and making the archive? If these
operations takes a significant amount of time themselves, the
preparation phase can also take a lot of time.

This is just a curiosity question. I have a long background in
systems software, mostly compilers but I have more than a passing
knowledge of operating systems.

Charlie
--
Nobody in this country got rich on his own. You built a factory--good.
But you moved your goods on roads we all paid for. You hired workers we
all paid to educate. So keep a big hunk of the money from your factory.
But take a hunk and pay it forward. Elizabeth Warren (paraphrased)

[Barry Margolin]

In article <1l2t2nh.1vz9bgg1qi1iq9N%csam...@inetworld.net>,

csam...@inetworld.net (Charles H. Sampson) wrote:

> There are a number of OS X operations that start with a preparation
> phase, during which a window is displayed with the phrase "Preparing to
> ..." Examples are copying a folder, emptying the trash, and making an
> archive. Does anyone know why they do this? Why don't they just start
> copying the folder, emptying the trash, and making the archive? If these
> operations takes a significant amount of time themselves, the
> preparation phase can also take a lot of time.
>
> This is just a curiosity question. I have a long background in
> systems software, mostly compilers but I have more than a passing
> knowledge of operating systems.

I think the difference is that it's safe to cancel an operation while
it's still "preparing" -- nothing has actually been changed yet. But if
you interrupt it while it's "doing", it may not be able to restore
everything to the initial configuration, so you end up with a
partially-changed system.

For instance, if you're moving a large number of files and cancel it in
the middle, you might end up with some files in the old location and
some in the new (maybe the Finder doesn't remove them from the old
location until it's all done copying them to the new location, so you
would end up with copies of some files in both places).

Another difference is that it may be able to display a progress bar for
the "doing" phase. But in order to figure out how much work needs to be
done, so that it knows how much progress is being made at each step, it
needs to prepare first. That message may be there to answer "Why is it
taking so long to display a progress bar?"

--
Barry Margolin, bar...@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

[Charles H. Sampson]

Barry Margolin <bar...@alum.mit.edu> wrote:

> In article <1l2t2nh.1vz9bgg1qi1iq9N%csam...@inetworld.net>,
> csam...@inetworld.net (Charles H. Sampson) wrote:
>
> > There are a number of OS X operations that start with a preparation
> > phase, during which a window is displayed with the phrase "Preparing to
> > ..." Examples are copying a folder, emptying the trash, and making an
> > archive. Does anyone know why they do this? Why don't they just start
> > copying the folder, emptying the trash, and making the archive? If these
> > operations takes a significant amount of time themselves, the
> > preparation phase can also take a lot of time.
> >
> > This is just a curiosity question. I have a long background in
> > systems software, mostly compilers but I have more than a passing
> > knowledge of operating systems.
>
> I think the difference is that it's safe to cancel an operation while
> it's still "preparing" -- nothing has actually been changed yet. But if
> you interrupt it while it's "doing", it may not be able to restore
> everything to the initial configuration, so you end up with a
> partially-changed system.
>
> For instance, if you're moving a large number of files and cancel it in
> the middle, you might end up with some files in the old location and
> some in the new (maybe the Finder doesn't remove them from the old
> location until it's all done copying them to the new location, so you
> would end up with copies of some files in both places).

But that's a general problem, isn't it? I don't see how doing any
sort of preparation would reduce the danger. You interrupt an operation,
you get the result of an interrupted operation.

> Another difference is that it may be able to display a progress bar for
> the "doing" phase. But in order to figure out how much work needs to be
> done, so that it knows how much progress is being made at each step, it
> needs to prepare first. That message may be there to answer "Why is it
> taking so long to display a progress bar?"

This makes sense. Still, it seems a high price to pay for a little
feedback. I regularly have to wait for over a minute -- which seems like
an eternity -- for the preparation stage of some things I do. I often
just go away and do something else. It's possible to do some of these
things with no preparation step. In Unix, if you cp a lot of files with
the options set the right way (no "verbose", for example), the cursor
just goes away until the copying is done. Unix users seem to find this
acceptable by and large. Unix users are a little odd, however.

[Barry Margolin]

In article <1l2v4g7.1twreoq1gr9uixN%csam...@inetworld.net>,

It doesn't reduce the danger, it tells you when it's safe -- you can
cancel during the preparation phase with no ill effects.