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> I am brand spanking new at Smalltalk.
Welcome!
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> I will be doing a lot of small exercises. How do I get back to the
> original image? (I did not backup the default image right after
> installing, so it already has some of the classes from the book in
> it. Do I have to uninstall and reinstall?
You can get a clean image by doing a "fresh install" from the Dolhphin start
menu. You don't need to re-install the Dolphin program itself. To make a copy
of an image, say it's called "Working", you need to make copies of the three
files:
Working.img
Working.sml
Working.chg
You can ignore the "Working.errors" file since it only contains a record of
each runtime error (normally resulting in a walkback dialog). Be careful to
keep these files in synch (if you make backups at all) since the .IMG file
contains pointers into the .SML and .CHG files.
The simplest way to do non-destructive experimenting is just not to save the
image as you exit Dolphin; that will result in *all* the changes you've made
(since you last saved) being discarded. Actually there is still a record of
what you did in the .CHG file, and -- sooner or later -- you will find yourself
needing to recover changes/actions from that file. Ian Bartholomew's Chunk
Browser is the best tool for doing that; the version for Dolphin 4 should be
at:
http://www.idb.me.uk/goodies4/goodies4.html
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> Can I delete classes from an image, or do I have to backup to a
> previously saved image, etc. to do that?
You can delete them as you wish. Not a good idea to delete, say, String
however...
BTW, I'd advise you to get into the habit of putting all classes (and any other
new code) into packages straight away. Unless it is genuine throwaway code
that you know you'll never want to think about again.
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> Are all the prepackaged classes that come with Dolphin standard
> procedure for ST environments, or Object-Arts variation?
There's a fair amount of commonality between Smalltalks for the core stuff
(like the Collections hierarchy), but, e.g, the GUI systems tend to be
completely different from one Smalltalk to another. As a *very* rough rule of
thumb, if any two ST implementations are the same in some respect -- have the
same classes or whatever -- then the chances are that Dolphin will be the same
as both of them. If any two differ in some respect then it's quite likely that
Dolphin will be different again from both of them. (This is a point to bear in
mind when you read Lui's book -- if you do -- since he discusses two or three
other implementations, but not Dolphin.)
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> Why do many people mention Smalltalk with such respect, and then use
> C++ or Java, or the MicroSoft stuff? At first blush, ST looks very
> good to me.
Market forces, ignorance, predjudice, inertia...
And personal preference too, of course.
-- chris