HELP EXIT                                      Aaron Sloman, August 1993

ENTER bye RETURN

    Is the most common way to exit Poplog

In order to exit from Poplog or its editor there are various different
commands, performing slightly different functions. Which command you
should use can also depend on which context you are in.

Further information follows.

         CONTENTS - (Use <ENTER> g to access required sections)

 -- 1. Quitting Poplog when using VED: ENTER bye
 -- 2. Quitting when typing to a language prompt
 -- 3. Quitting each file separately
 -- 4. ENTER qq (quit but check first)
 -- 5. ENTER xx is the same as ENTER bye
 -- 6. If Poplog is stuck in an uninterruptable loop
 -- 7. The obsolete Pop-2 syntax word "EXIT"

-- 1. Quitting Poplog when using VED: ENTER bye -----------------------

If you are using the Poplog editor VED, and you wish to leave the
editor and terminate the Poplog session, you can type

    ENTER bye RETURN

I.e.
    (a) press the ENTER key (usually on the right of the keyboard)
        (This should move the cursor to the command line)
then
    (b)type the characters: bye
then
    (c) press the RETURN key.

If the ENTER key does not move the cursor to the "command" line you can
try using CTRL-G (I.e. hold down the button marked "CTRL" or "Control",
which is usually somewhere on the left of the keyboard, and without
releasing it press the G key, then release both.

Note the "ENTER bye" command will cause the editor to check whether you
have any files that you have been working on that have been modified but
whose changes have not yet been saved to the magnetic disk (the long
term file store). If there are any such files, then they will
automatically be saved.


-- 2. Quitting when typing to a language prompt -----------------------

If you are not in the editor and are typing to the Pop-11 prompt

    ":"

then you can leave Pop-11 and Poplog by typing the END-OF-FILE
character, which on Unix systems is usually CTRL-D, on VMS CTRL-Z.

If you are not using Pop-11 but one of the other Poplog languages, and
are typing to its prompt, outside the editor, you can also quit in that
way.

Pop-11, Poplog ML, and Poplog Common Lisp also accept the command

    bye

followed by pressing the RETURN key, as an instruction to exit, and
Poplog Prolog accepts the same command followed by a "full stop"
character:

    bye.

    Note that this use of BYE will not work if you are typing in a VED
    "immediate mode" file. All it does in that context is terminate
    immediate mode. In that case use method 1 to exit Poplog i.e.

        ENTER bye RETURN

    (For more on "immediate mode" see HELP * IM)

-- 3. Quitting each file separately -----------------------------------

If you have been working on several files but you don't want all of them
to be saved, you can try quitting the files one at a time by typing, in
each file:

    ENTER q RETURN

    (Or ESC q, if you are not using LIB VEDEMACS)

For each file that has been changed but not saved, VED will ask you:

    (FILE CHANGED. WRITE IT? TYPE 'y', 'n', OR 'c' TO CONTINUE )

If you type:
    "y"     -  VED will write the file and quit it.
    "n"     -  VED will quit without writing the file
    "c"     -  VED will abort the attempt to quit, and allow you to
                   continue editing

If you quit all your files this way you will eventually end up with
the Pop-11 prompt (or if you are using Prolog, or Lisp, or ML, the
prompt for the language in question.)


-- 4. ENTER qq (quit but check first) ---------------------------------

If you wish to quit completely, but want to be given a chance to
say No if there are any changed but unwritten files, type

    ENTER qq  RETURN

This quits both VED and Poplog, but first checks whethere are unwritten
files, and then prompts in the same way as the "ENTER q" command.

-- 5. ENTER xx is the same as ENTER bye -------------------------------

ENTER xx RETURN

This is the same as ENTER bye RETURN (i.e. eXit VED then eXit Poplog).


-- 6. If Poplog is stuck in an uninterruptable loop -------------------

If for some reason Poplog is stuck in a loop and is printing out
error messages which you cannot interrupt with the interrupt character
(usually CTRL-C) then you can try the Quit character, which on Unix
is usually set to CTRL-\ (I.e. "\" is the "backslash" character), and
on VMS is usually set to CTRL-Y.

If you type it once, it should stop the loop and invoke "setpop" to
reset Poplog. If that doesn't work you can type it twice in quick
succession (ie. less than about half a second). That should cause
Poplog to abort and take you back to the Unix or VMS command line.

The terminal handling software may then not be set right. For instance
it may not be echoing what you type. In that case you should probably
(on Unix) give the "tset" command to reset it. I.e. do the following to
reset:

    1. Press the LINEFEED or LF key (or CTRL-J if there isn't such a key)

    2. Type the following (which may not echo): tset

    3. Then press LINEFEED (or LF or CTRL-J) again.


-- 7. The obsolete Pop-2 syntax word "EXIT" ---------------------------

The word "exit" used, in Pop-2 to be equivalent to

    return(); close();

In Pop-11 it does not exist, though "return" can still be used to cause
a procedure to finish and return control to the procedure that called
it.


--- $poplocal/local/help/exit
--- Copyright University of Birmingham 1993. All rights reserved. ------
