[Newbies] Squeak Learn Programing with Robots

[David T. Lewis]

On Mon, Mar 04, 2019 at 03:19:50PM -0500, Robert Kuropkat wrote:
> On Mon, 4 Mar 2019 12:54:48 -0500
>  "David T. Lewis" <lewis at mail.msen.com> wrote:
> >On Sun, Mar 03, 2019 at 07:42:29PM -0500, Robert 
> >Kuropkat wrote:
> >>On Sun, 2019-03-03 at 13:47 -0500, David T. Lewis wrote:
> >>> On Sat, Mar 02, 2019 at 03:48:25PM -0500, Robert 
> >>Kuropkat wrote:
> >>> > Is there an updated Ready.image file (the one that goes with the book)
> >>> > that works with the latest Squeak?  I'm looking to teach a class and
> >>> > wanted to use this book, but at first blush, the image does not seem to
> >>> > work with Squeak 5.2 (on Linux at least).
> >>> 
> >>> Hi Robert,
> >>> 
> >>> I do not remember anyone mentioning an update to the image, so I suspect
> >>> that the original image that came with the book would be the one to use.
> >>> 
> >>> The most recent VMs for Squeak will probably not run an image from that
> >>> era, but if you are using Linux for the class, it will not be difficult
> >>> to provide a compatible VM.
> >>> 
> >>> If the Ready.image is available for download, could you please give a
> >>> link to the download site? I would be happy to take a look at it and
> >>> suggest a suitable VM for running that image.
> >>> 
> >>
> >>I retrieved the download from here: https://github.com/apress/squeak  I
> >>grabbed the ReadyPC-05052005.zip.  It worked fine on Linux using the
> >>latest Squeak v3.  It would not work in v4 or v5.  I was also planning
> >>to use Squeak By Example (which I believe is v4 era) as well as other,
> >>more modern examples for a beginner class.  Version 3, 4 and 5 are all
> >>available for Windows, Mac and Linux.  I **could** have students
> >>install all three versions (I did that on Linux) but was kind of hoping
> >>to avoid that if it was possible to port these images to v5.
> >>
> >>The ReadyPC zip file contains the following:
> >>
> >>luth.frm  Ready.changes Ready.image  spider.frm Squeak.exe  SqueakV3.sources
> >
> >Hi Robert,
> >
> >As far as I am aware, the images that go with these books are not being
> >actively updated for newer versions of Squeak. But aside from the inconvenience
> >of installing multiple versions, there should be nothing wrong with using
> >those images exactly as they are. They should work fine, and by using the
> >old images you can be more confident that the systems will work as
> >described in the books.
> >
> >I downloaded the zip for Ready.image, and the image seems to work fine with
> >the interpreter VM that I have installed on my Linux PC. This is a VM
> >that I compiled from latest sources, so I am confident that if the
> >VMs that you are using with the book distributions do not work properly,
> >then an updated VM for Linux can be provided (and I would be happy to
> >help with that if needed).
> >
> 
> David,
> 
> You make a solid point about sticking with the version of 
> Squeak the image was made for.  So for the purpose of the 
> class, I may well do so.  Installing and running different 
> versions of Squeak might be a lesson in itself.
> 
> However, did I understand correctly that you were able to 
> use the Ready.image with Squeak v5-ish?  If so, that means 
> I'm doing something wrong, so would love to get educated 
> on that issue.
> 

Hi Robert,

I think that we are mixing terms a bit with respect to Squeak
versions, so let me clarify what I was saying. When I speak about
a version of Squeak, I am thinking mainly of the image itself (the
squeak.image file and its companion squeak.changes file).

The VM (virtual machine) is the execution engine for that image,
and in general terms, any given version of Squeak (the image) will
run on any of several VMs, and any given VM will be able to run
various versions (but not all versions) of Squeak images.

For example, if you point your web browser to http://try.squeak.org
you will find a web based VM written in JavaScript that is able
to run a very wide range of Squeak versions. The VM is completely
different from the one that you might install on your Linux or
Windows PC, but it runs the Squeak images exactly as if they were
running on a traditional compiled VM.

If you are working with a Squeak image that was distributed with
a book, then you probably have both the image itself, and possibly
several VMs from that time period. You can be confident that the
image itself will still work well today, and probably for many more
years in the future. However, any VM that was distributed 10 years
ago or more may be in need of an update, due to changes in operating
systems and runtime libraries for those operating systems.

This is the reason that I wanted to test your Ready.image on a recently
compiled VM on my PC. This confirms that the image works, and also
that it would be possible for you to recompile a new version of the
VM for that image if you needed to do so,

In general, you will find that old VMs for Windows will work reliably
for many years, but VMs for Linux will need to be recompiled more
frequently.

Assuming that you are using Linux PCs for the class that you are planning
to teach, I would say that if you have a working image and VM combination,
then just use it. But if you do find problems using an older VM on Linux,
then I am confident that an updated VM can be provided (and I can help
with that).

Dave