LOGO-L> Re: SAVE, LOAD & 'UNDO'?

[George Mills <mills@softronix.com>]

Regarding undo,

Keep in mind that Logo is both an interactive drawing program
and a programming language. It won't be long before your writing
procedures to do all the work rather than typing in a command
for each line. When you get to that point you won't care much about
"Undoing" a drawn line because you'll just erase the whole screen
and call your program to draw the whole thing again (with the
correction).

"Undo" in the drawing side of logo is possible, but it's expensive
and would slow down drawing. When you start writing procedures
that draw you won't want to pay that penalty. It would be more
useful to have the procedure editor have "undo" which it does have
but only a single level undo.

You can "erase" a line by issuing the command PENERASE and backing
up over the line. Then type PENNORMAL to restore the pen.

Example:

FD 100
RT 90
FD 100
PENERASE
BK 100
PENNORMAL
FD 50

Also read about PENREVERSE in the online help.

Regarding Save and Load,

Save and Load is confusing for many beginners.
Below is a previous response to your question.
But before you read it keep in mind that MSWLogo
"Projects" are not pictures nor are they recordings
of the commands you executed. They are a collection
of procedures you wrote (defined). It sounds as if
you may not of defined any procedures yet, so there
is nothing to save and load. If you have defined
procedures but are still having problems I hope the
message below will clear that up as well.

Note that I am CCing this message to logo-l@gsn.org
which is a mailing list for all versions of logo.
See MSWLogo's web page (see bottom of this message)
on details of how to join (there are several home
schoolers on that list as well). You might also be interested
in Jim Mullers book called "The Great Logo Adventure"
which is great for beginners (info also available on
MSWLogo's web page).

*************** This is extracted from a previous post to logo-l
****************

Typing code into the Commander Input Box does not save your code.
It just runs the command you typed in.

To save your "code" you need to define procedures
that contain your code and then save those definitions
to the disk.

You define procedures by entering something like this
in the Commander Input Box.

EDIT "HELLO

This brings up an editor with an empty definition
for HELLO (if it did not already exist).

Now put your code between the TO HELLO line and the
END line.

Example:

TO HELLO
PRINT "GoodDay
END

Now exit the editor and save it.

Now run HELLO by entering HELLO in the Commander Input Box followed by
Execute button or <Enter> key. Just like you would any logo command.

HELLO
Goodday

You've just extended the logo language by adding a new command
to logo called HELLO.

Now make a change

EDIT "HELLO

TO HELLO :msg
PRINT :msg
END

Exit the editor, save it and run it again

HELLO "Goodbye
Goodbye

Now it is NOT saved to the disk drive yet for another days usage.

SAVE "HELLO.LGO
BYE

Start logo again and reload the definitions you saved.

LOAD "HELLO.LGO

Now you can edit it or run it.

You can also use EDALL instead of EDIT
which will bring up all your procedure definitions.

If you typed a bunch of "code" into the edit box that
you want to create a procedure out of. Then select the
text with the mouse and hit <CTRL-C> which copies the
code to the clipboard.

Now open up the editor (EDALL) and paste the text into
a new procedure (bewteen a TO line and END Line).
Usually when you do this you tend to clean up the
code you copied.

If you use EDALL and delete a definition from the editor
that definition will be removed. What You Edit Is What You Get.

You can also delete a definition from the commander or File Menu.

ERASE "HELLO

Note SAVE, LOAD, EDIT, EDALL and ERASE can all be done through
the file menu. Save and load tend to be easiest through the menu
while issuing EDALL from the commander input box is all you
need for all procedure maintainance.

skyryder wrote:
> 
> Hi!   Greetings from UK!
> 
> My MSWLogo will not save or load - is there a trick to it?
> 
> Also is there a way for 'undoing' the last line drawn?
> 
> My nearly-eight-year old friend, Randy (aka daughter) and I are
> home-educating each other and find your MSWLogo extremely potent yet so
> FRIENDLY!  She is so drawn in (little pun) that within three sessions we
> were shaking hands HAPPILY with  Ole' Man Pythagoras as well as delving into
> Trig [when trying to calculate the length of a diagonal of a rectangle and
> its angle - Randy was drawing the famous 'open envelope' as her second
> mini-project].
> 
> We thank you for giving us MSWLogo and for your obvious enthusiasm!
> 
> Sky and Randy

-- 
===============================================================
George Mills
email: mills@softronix.com
http://www.softronix.com
The www page contains some very powerful educational software.
Our single most important investment is our kids.
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