Sprite 1984 - 1993/Sprite 1984 - 1993.iso/lib/mx/tutorial1

Text File | 1989-12-22 | 24KB | 420 lines

          --------------------------------
                   Mx Tutorial #1:  Basic Editing
          --------------------------------

                         by John Ousterhout

This document is an introduction to Mx, which is a mouse-based editor for
use with the X window system.  The best way to read this tutorial is on-line
in an Mx window, so that you can try out the commands as they are introduced.
To access this tutorial on-line, invoke the shell command "mx" with no
arguments.

Simple Scrolling:
----------
The first thing for you to learn is how to move around within a file, so that
you can at least read the tutorial.  This is called "scrolling".  The easiest
way to scroll is by "dragging" the document:  hold down the shift key with
your left hand, place the pointer over the center of this window, press the
left mouse button, and move the mouse up and down while holding the button
down.  As you move the mouse, the document will move up and down in the
window.  In the shorthand notation I'll use in the tutorial, what you just
did is called "shift-left-dragging".  If you'd like to move the document
more quickly, for example to browse through it quickly, try
shift-right-dragging (use the right mouse button instead of the left).  In
this case, the document will move a lot in response to very small mouse
motions.

The vertical strip on the right side of the Mx window is called the
"scrollbar".  A thin vertical rectangle is displayed inside the scrollbar.
I call this the "elevator".  Its height and location indicate which portion
of the file is visible in the window.  For example, if the top of the
elevator is at the top of the scrollbar and the bottom of the elevator
is halfway down the scrollbar, it means that the first half of the file
is visible in the window.  Try dragging up and down and see how the elevator
moves.

You can also scroll by pressing mouse buttons with the pointer over the
scrollbar.  If you move the pointer over the scrollbar and then "middle-click"
(press the middle mouse button and then immediately release it) the view will
change so that the center of the elevator is at the pointer position.  If you
left-click in the scrollbar, the contents of the window will move up so that
the line that used to be next to the pointer is now at the top of the window.
Right-clicking is the inverse of left-clicking:  it moves the contents of the
window down so that the line that used to be at the top is now next to the
pointer.  If you have a reasonably fast display, you'll probably find that
it's more convenient to scroll by dragging than by clicking in the scrollbar.

Basics:
-------
Mx is a simple editor that allows you to examine and modify text files.  It
provides basic editing functions such as insertion, deletion, copying,
searching, and substitution.  It also supports multiple windows.  You can
display several different files at the same time in different windows and
copy information back and forth between them, and you can look at several
different regions of the same file at the same time using a different
window for each region.

Each Mx window contains several subwindows.  The top-most subwindow is
normally a title bar displayed by the window manager;  it may also be
a title bar displayed by Mx, if you've specified the value "yes" for the
"showTitle" X default.  The title bar displays the name of the file
you're editing.  If you've modified the file, then an exclamation point
will appear after the file's name (or the word "Modified" will appear
at the right side of the title bar).  Just underneath the title bar is
the "menu bar", which contains the names of several pull-down menus,
and underneath that is a message window, which currently gives the name
and size of this file. Information and error messages will appear in
the message window at various times during editing.  At the right side
of the window is the scrollbar, which you're already familiar with.
The rest of the window displays a few lines of the file you're editing.
A few other subwindows will appear later on, while you're editing. For
example, one of them will be used to enter strings for searching and
replacement.

There are three ways that you can invoke operations in Mx: by positioning the
pointer over the text of the file and clicking or dragging with the mouse, by
typing keys on the keyboard, or by selecting menu entries with the mouse.
For a simple example of each of these, first move the pointer over the leftmost
"X" in the line below and left-click.  A little upside-down "V", called the
"caret", will appear just to the left of the X.

            XXXX - play here

Second, type some characters on the keyboard.  Each keystroke invokes an Mx
command to insert that character into the file just before the caret.  As
you'll see later, various special keys, such as the control keys, can be used
to invoke other Mx commands such as copying and deleting text.  Finally, for
an example of a menu selection, move the pointer up to the menu bar (it's
the horizontal strip at the top of the window just underneath the striped
title bar), and position it over the word "Control".  The word will highlight.
Press the left mouse button and hold it down.  This causes a menu to appear
underneath the pointer.  With the button held down, drag the pointer down
through the menu until the word "Undo" is highlighted, then release the mouse
button.  This invokes the undo command, which will remove all the text you
just typed in.

Each word in the menu bar corresponds to a different menu.  To scan through
the menus, press the left mouse button with the pointer over "Control", and
hold the button down.  Then drag the pointer to the right so that it passes
in turn over each of the other words in the menu bar.

When an error occurs while Mx is executing a command, Mx will tell you in
one of two ways.  For short messages, Mx will place the message in the message
subwindow.  For an example of this, type control-Z on the keyboard:  there's
no Mx command associated with this keystroke.  If an error message is long,
or if Mx needs for you to make a decision, it will pop up a special window
called a "notifier".  The notifier contains a message plus one or more options,
which appear at the top of the notifier.  When you see a notifier, you must
click on one of the options in order to tell Mx what to do.  Your screen will
be frozen until you've responded to the notifier.  For example, insert some
characters in this file then invoke the "Quit" entry in the "Control" menu.
A notifier will warn you that you're about to lose the changes you just
made to this file.  Click a mouse button on the "Skip command" option.

The Caret and Insertion:
------------------------
The simplest operation in Mx is insertion.  If you type normal characters on
the keyboard, they will be inserted in the file at the position of the caret.
You can position the caret anywhere in the file by left-clicking or
left-dragging.  If you make mistakes while you're typing, you can type
control-h, BACKSPACE, or DELETE to delete the character just before the caret.
Control-w will delete the entire word that precedes the caret.  Try inserting
text at various positions within this file.

The Selection:
--------------
The selection is a special range of text used in operations like copying
and deletion.  To select a range of characters, position the caret at one
end of the range, then move the pointer to the other end of the range and
right-click.  All of the characters between the caret and the pointer will
become highlighted.  These characters constitute the selection.  Try changing
the selection by moving the pointer somewhere else and right-clicking.  You
can drag the end of the selection by moving the mouse with the right button
held down, just as you can drag the caret by moving with the left button
down.  Try selecting various ranges of text in this tutorial.  There can
only be one selection at a time:  when you make one selection, the previous
one disappears.

There are additional selection modes called "word selection" and "line
selection".  To invoke word selection, point to a character in the middle of
a word and left-click twice in a row (quickly) without moving the mouse.
This is called "double-clicking", and will cause the entire word to be
selected.  When you right-click now, Mx will ensure that only whole-words
are selected.  If you triple-click the left button, then Mx will force the
selection to consist of entire lines of the file.  Try making word and line
selections.

A word is any collection of adjacent letters and digits.  Each punctuation
character is considered to be a word by itself, except that the bracket
characters "()[]{}<>" are treated specially.  When you use word selection
on a bracket character, Mx finds the matching bracket and selects the entire
range, including the open and close brackets.  Brackets may be nested.
Double-click in the code fragment below and hold the left button down during
the second click.  Then drag the pointer around to see what happens when it
passes over the various brackets:

        if (template != NULL) {
            x = (foo[index+2, y] + (x/y)*42)/(y+1);
            y = 0;
        }

If you only want to select a single character, there is a faster way than
first left-clicking to position the caret at one side of the character and
then right-clicking to select the character.  Instead, "roll" the mouse
buttons: press left then immediately press right before you've released left.
This will select the character under the pointer and also place the caret
at the left side of the character.  If you hold one or both of the mouse
buttons down after you've rolled, you can drag both the caret and the
selection.

There are times when it's convenient to make a selection without moving
the caret (e.g., you've already got the caret where you want it and you'd
like to select some text to copy to the caret position).  To do this, hold
the control key down while you select.  Control-left-click will select the
character under the pointer without moving the caret, and control-right-click
will select the range of characters between the pointer position and the
character that you selected with control-left-click.

Copying and Deleting:
---------------------

The selection is used for many purposes in Mx, the most common of which are
deleting and copying.  You can delete a range of text by selecting the text
and then invoking the "Delete $sel" entry in the "Selection" menu.  Throughout
the Mx menus, the term "$sel" refers to the selection.  Note that you can
select the newline character at the end of a line (when it's selected, all of
the white space at the end of the line is highlighted);  if you delete the
newline character, the following line will be joined to the current line.

The "Copy $sel to caret" entry in the "Selection" menu will insert a copy of
the selection at the position of the caret, and the "Move $sel to caret"
entry in the "Selection" menu will move the selection to the caret position.
Some people find it most convenient to first select the text to be copied
or moved and then position the caret at the destination;  others find it more
convenient to position the caret first, then hold the control key down while
selecting the text.  Try using copy and delete to exchange the words "red"
and "house" in the sentence below.  Then use move to put "red" back where it
was originally.

        Thank goodness they're repainting their house red.

Saving Files and Leaving the Editor:
------------------------------------
When you're ready to leave the editor, select the "Quit" entry in the
"Control" menu.  This will destroy the X window.  It will also end the
execution of Mx, if there are no other Mx windows open.

When you make changes to a file in Mx, those changes are not automatically
reflected in the original copy of the file on disk.  To change the disk
version of the file, you must "save" the file.  The "Save" entry in the
"Control" menu will write the file back to disk.  Or, if you've modified the
file and then try to quit without saving the file, Mx will warn you with
a notifier and give you a chance to save the file or skip the quit command.

If you'd like to save the edits in a different file than the one you started
out with, select the name of the file you'd like to save into and then invoke
the "Save in file $sel" entry in the "Control" menu.  The only problem
here is how to get the file name someplace where you can select it.  If it
already appears on the screen somewhere, just select it.  If you use Tx for
your terminal emulator, you can type the file name in a Tx window and
select it there.  As a last resort, open the command subwindow by invoking
the "Open command subwindow" in the "Window" menu.  The caret should
appear in the small subwindow that just appeared at the bottom of the
window.  Then type the file name there and select it for use in saving
the file.  After saving the file, you can make the command subwindow go
away by getting the caret into the command subwindow (if it isn't there
already, invoke the "Open command subwindow" menu entry again, or left-click
in the command subwindow) and typing control-q.  In general, typing
control-q in an Mx window or subwindow is a request to make the (sub)window
go away.

Bindings:
----------
The menus are convenient for learning because they're easy to browse through
to find commands.  However, if you use the menus a lot you won't be able to
edit very quickly.  Fortunately, many of the Mx commands can be invoked
by typing keys as well as by selecting menu entries.  The keystrokes are
called "bindings":  a particular key or sequence of keys is "bound" to an
Mx command.  If there is a keystroke sequence equivalent to a menu entry,
the binding appears at the right side of the menu entry.  For example, the
"Copy" entry in the "Selection" menu shows the binding "C-v", which is an
abbreviation for "control-v".  The "Delete" entry in the same menu has the
binding "control-d".  These two bindings and the control-q binding
mentioned above are the most important ones;  I suggest that you learn
them immediately and use them instead of the menu entries.  You can
gradually learn other bindings as you become more familiar with the system.
To get information about all of the default bindings, invoke the "Info on
default key bindings" entry in the "Help" menu.

The binding "M-v" in the "Selection" menu means "meta-v", which means
different things on different keyboards.  On Sun-3 keyboards, "M-v" means
first press either the "Left" or "Right" key (next to the space bar),
then press "v" while holding down "Left" or "Right".  The term "ESC" refers
to the escape key.  For example, the binding "ESC f" means first type the
escape key, then the "f" key.

You can change the bindings to eliminate old ones and define new ones if
you wish.  You can also modify the menus, or even change the meanings of
normal keystrokes (for example, you could arrange things so that typing
the space character caused the selection to be deleted, if that turned out
to be desirable).  For more information on how to do this see the "bind"
command in the Mx manual entry.

Undoing and Crash Recovery:
---------------------------
While you edit, Mx keeps a log of every modification that you make to the
file.  The log is used for two purposes:  undoing and recovery.  If you ever
make a change and then wish you hadn't, you can invoke the "Undo" entry in
the "Control" menu or type the "C-u" binding.  This will cause the last
modification you made to the file to be undone.  If you undo several times
in a row without any intervening file modifications, each invocation will undo
the next older action, all the way back to the beginning of the edit session.
Make a series of changes to this file, then undo them.

Normally, each user-invoked action, such as a keystroke or button click or
menu selection, constitutes one event as far as undoing is concerned.  Thus
if you copy a huge selection, the whole copy will be undone at once.  The
only exception to this rule is that if you type in a bunch of text on the
same line, then all of the text will be undone together (i.e. you don't have
to invoke undo once for each character; use backspace or control-W if you
only want to erase a few characters).  If you type in many lines of text in
a row, then the type-in will be undone one line at a time.

The undo actions are recorded in the log, so they can be undone also. However,
if you undo something and then wish you hadn't, you can't just undo again:
that will undo the next next older action, rather than undoing the undo.
Instead, hit the space bar, which inserts a space character in the file.
This (or any other modification to the file) resets the undo mechanism so that
the next undo refers to the most recent modification to the file;  now invoke
undo twice:  the first will undo the space insertion and the second will undo
the unwanted undo.

The second purpose of the log is to allow recovery if Mx crashes during an edit
session or if your machine goes down unexpectedly.  If a crash occurs, the
log file will be left on disk.  The log file has a name beginning with "Mx"
and is usually stored in the directory containing the file being edited.  If
that directory isn't writable, then Mx stores the log file in your home
directory.  To recover all the changes you made during a crashed edit
session, just re-run Mx on the same file.  Mx will locate the log file and
pop up a notifier giving you the choice of recovering or deleting the old
log file.  If you select recovery, Mx will scan through the log file and
update the file to reflect all of the changes made in the crashed edit
session.  With the recovery mechanism, you should never lose any modifications
except for those on the line where you were working when the crash occurred.
You can try out the recovery features by starting up Mx and then killing it
from the shell.

Searching and Substitution:
---------------------------
Mx provides mechanisms that allow you to search through a file for a
particular sequence of characters, or to replace a given sequence of
characters with another sequence provided by you.  To see how this works,
invoke the "Search forward" entry in the "Search" menu.  The first time you
invoke this operation, Mx will open a new subwindow just under the menu bar,
called the "search subwindow".  It contains two entry areas, where you can
type in a search string and a replacement string.  To enter a search string,
get the caret into the search entry (if it isn't already there) by moving
the pointer over the entry and left-clicking.  Now you can type in a search
string.  The editing characters "C-h" and "C-w" work in the search subwindow,
and you can also use the selection and "C-d" to edit the search and
replacement strings.  You can use "C-v" to copy information from almost
anywhere on the screen to the search and replacement strings.

Enter the characters "the" as the search string.  There are four different
ways you can invoke searching now.  The simplest is to re-invoke the "Search
forward" entry in the "Search" menu.  Mx will search for the next occurrence
of the string "the", starting at the caret location, and will select that
occurrence.  You can also search using the "C-f" binding, or by typing
RETURN when the caret is in the search string, or by middle-clicking on the
search string.  These four approaches all produce the same result.  The
"Search" menu provides a "Search backward" entry to scan in the opposite
direction.  If one end of the file is reached during a search, Mx skips to
the opposite end of the file and continues.

If you don't want to type the search string into the search subwindow, you
can also select the string you'd like to search for and use the "Search
forward for $sel" and "Search backward for $sel" menu entries.

To make substitutions, enter a replacement string into the search subwindow
and invoke the "Replace" command in the "Search" menu.  This will replace
the selection with the replacement string.  You can also invoke replacement
by typing RETURN in the replacement string, by middle-clicking on the
replacement string, or by typing the "C-r" binding.

By default, search and replacement strings are regular expressions in
the style of the vi text editor.  If you'd prefer for searching and
replacement to be done by exact matches only, without regular expressions,
set the "noRegExps" variable to 1.

If you'd like to replace all the instances of one string by another string,
you have two choices.  One possibility is repeatedly to type "C-f" and "C-r"
to step through the instances one at a time.  Or, you can select a range of
text in which you'd like to make the substitution and invoke the
"Substitute throughout $sel" entry in the "Search" menu.  This will replace
all instances of the search string in a single operation.  Try using these
commands to replace "the" with "my" in several areas of this document.
The "Substitute everywhere" entry in the "Search" menu will make the
substitution throughout the file.

Two other bindings are useful when searching and replacing:  "ESC-f" will
clear the search string entry and move the caret there, so you can type
in a new search string;  and "ESC-r" will clear the replacement string
entry and move the caret there

When you no longer need the search subwindow, you can get rid of it by
getting the caret into it (left-click on the window if necessary) and
typing "C-q".

Using Multiple Windows:
-----------------------
Mx allows you to open several windows on the same or different files and
copy information back and forth between them.  Invoke the "New window on same
file" entry in the "Window" menu.  The new window will display the same file
as the old window, and you can modify the file from either window.  Try making
changes in both windows:  you'll see the selection and the changes in each of
the windows.  You can also open a new window on a different file by selecting
the file's name and invoking the "New window on $sel" entry in the "Window"
menu.  Once this is done, you can use the selection to copy information back
and forth between the windows.

The "Window" menu also includes additional entries for switching the current
window from one file to another ("See file $sel"), opening a new window (or
switching the current window) to display the definition of a symbol using the
tags facility, and adjusting the view in a window to display a particular line
number (e.g. for compiler error messages).

Indentation:
------------
Mx automatically manages line indentation.  Whenever you type RETURN to start
a new line, Mx will indent the new line to match the indentation of the
previous line.  Whenever you move the caret away from a line Mx will clean up
the line's indentation:  if there is any white space at the beginning of the
line, Mx replaces as much of it as possible with tabs (one tab for each eight
spaces).  In the lines below, position the caret at the end of the various
lines and type RETURN to see how auto-indentation works:

        This line is indented.
            This line is indented even more.

The "Indent" menu provides several commands to modify the indentation of
lines.  "Indent selected lines 4" will shift all the lines in the selection
right by 4 spaces, and "Outdent selected lines 4" will shift the lines left
by 4 spaces.  "Indent caret line 4" and "Outdent caret line 4" do the same
thing for the line containing the caret.  The last menu entry will eliminate
all indentation in the selected lines.

History and Repeating Commands:
-------------------------------
Mx automatically records commands you've invoked so that they can
be replayed later.  For full details, read about the "history" command in
the manual page.  The simplest mechanism is "Do again", which is
available in the "Control" menu or with the "C-a" binding.  This will
repeat all the commands you invoked between the last two button presses,
searches, or undos.  For an example of how this works, select "Test"
below, then delete it and type "Foo" in its place.  Then select "Test2",
and type "C-a";  you can continue with "Test3" and "Test4" also.

        Test        Test2        Test3        Test4