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Smalltalk/X
_________________________________________________________________
o What Is Smalltalk/X?
o How To Install Smalltalk/X
o Invoking Smalltalk/X
o Getting Around in ST/X
o The Browsers Options
# The System Browser
# The Class Hierarchy Browser
# Implementors
# Senders
# The Changes Browser
# Directory Browser
o The Workspace Option
o The File Browser Option
o The Projects Option
o The Utilities Option
o The Goodies Option
o The Games & Demo Option
o Editing in Browsers
o Using the Inspector
o Using the Debugger
o Summary
_________________________________________________________________
34
Smalltalk/X
This chapter describes Smalltalk/X (ST/X), a fairly complete
implementation of the Smalltalk-80 programming environment. Anyone who
has used Smalltalk-80 or any other version of Smalltalk will be
impressed with this freely available implementation. In this chapter
we will see
* What Smalltalk/X is
* How to install Smalltalk/X
* Invoking Smalltalk/X
* Getting around in Smalltalk/X
This chapter gives you an overview of the Smalltalk/X application.
After reading the chapter you should be familiar with the facilities
that Smalltalk/X provides and be able to navigate your way through the
Smalltalk/X user interface.
What Is Smalltalk/X?
When describing Smalltalk/X, it is probably appropriate to start with
a description of Smalltalk itself. Smalltalk is an object-oriented
programming language that has been a continuing development project at
ParcPlace Systems since the early 1970s. Although it was not the first
object-oriented language, it was the first object-oriented language to
gain wide use in the industry.
Smalltalk has been around for about 15 years now but it was not until
recently that it started to become popular. Many universities now
teach a Smalltalk course as part of their standard computer science
curriculum, and many companies have seen the value that Smalltalk adds
in terms of quick development.
Smalltalk/X was developed by Claus Gittinger and was first released in
1988. It is almost identical to the behavior of the Smalltalk 80
implementation of the Smalltalk language. Smalltalk/X comes complete
with an application launcher, several different browsers for browsing
through the Smalltalk class hierarchy, and a very powerful debugging
utility. The unique aspect of Smalltalk/X is that it can also behave
as a Smalltalk-to-C translation utility. This is a very useful feature
because this means that you will be able to combine the speed of
development that Smalltalk provides with the speed of execution that C
provides.
How To Install Smalltalk/X
Before installing Smalltalk/X, you must first retrieve it from
sunsite.unc.edu in the /pub/Linux/devel/lang/smalltalkx directory.
Once there, you will find the following files:
* COPYRIGHT As the filename suggests, this is the SmallTalk/X
copyright information document.
* INDEX Provides a list of files in the directory.
* LICENSE The distribution license for SmallTalk/X.
* README Contains a brief discription of how to get SmallTalk/X
running.
* bitmaps.tar.Z Contains sample graphics that can be used to dress
up the visual appeal of your programs.
* doc.tar.Z The documentation set for SmallTalk/X. This package also
includes several demos.
* exe.tar.Z The executable archive. Although this is really the only
file you need to download to get SmallTalk/X up and running,
installing the bitmap, documentation, goodies, and source files is
also highly recommended.
* goodies.tar.Z Various extras thrown in for your enjoyment.
* source.tar.Z Support and library files needed to get the most out
of SmallTalk/X.
To install Smalltalk/X, perform the following steps as root.
1. Create a directory called /usr/local/lib/smalltalk.
2. Copy the following files into the /usr/local/lib/smalltalk
directory.
bitmaps.tar.Z
doc.tar.Z
exe.tar.Z
goodies.tar.Z
source.tar.Z
3. Uncompress and untar these files by entering the following
commands from the /usr/local/lib/smalltalk directory.
uncompress *.Z
tar -xf bitmaps.tar
tar -xf doc.tar
tar -xf exe.tar
tar -xf goodies.tar
tar -xf source.tar
4. You can now delete all of the tar files by typing the following
command:
rm -f *.tar
5. Finally, create the following links:
ln /usr/i486-linuxaout/lib/libc.so.4 /usr/lib/libc.so.4
ln /usr/i486-linuxaout/lib/libXt.so.3 /usr/lib/libXt.so.3
ln /usr/i486-linuxaout/lib/libxll.so.3 /usr/lib/libxll.so.3
ln /usr/i486-linuxaout/lib/libm.so.4 /usr/lib/libm.so.4
The Smalltalk/X program should now be installed and ready to go.
______________________________________________________________
NOTE: If you do not have write access to the /usr/local/lib
directory, install Smalltalk/X in some other directory by following
the same steps listed above. If you do this you must set the
SMALLTALK_LIBDIR variable to be equal to the new directory.
______________________________________________________________
Invoking Smalltalk/X
You invoke Smalltalk/X by typing
smalltalk
in an Xterm window from the /usr/local/lib/smalltalk directory. When
ST/X starts, it checks to see if there is an image file for it to use.
If it cannot find an image file, it uses a file called smalltalk.rc to
set up the default behavior for your environment. The image file that
is loaded by default is called st.img, and contains a snapshot of what
your ST/X environment looked like the last time you exited. This
allows you to resume exactly where you left off. You can save a
snapshot under any name with the extension .img. To invoke ST/X with
an image other than st.img, type the following command at the prompt:
smalltalk -i nameofImage.img
Getting Around in ST/X
Once ST/X is invoked, two windows or views will appear. The Transcript
view and the Launcher menu. The Transcript view is shown in Figure
34.1.
Figure 34.1. The Transcript view.
The Transcript is the console where relevant systems information is
shown. The Launcher menu is shown in Figure 34.2.
Figure 34.2. The Launcher menu.
The Launcher allows access to the tools you will need to program your
application. Table 34.1 gives the options available from the Launcher
and a brief description of each.
Table 34.1. The Launcher menu options.
Option Description
Browsers The pull-right menu of this option gives you access to
browsers, senders, and implementors.
Workspace This option brings up a workspace view.
FileBrowser This browser allows inspection and manipulation of files
and directories.
Projects This option allows you to choose an existing or new project.
Utilities This contains tools specific to your programming needs.
Goodies This contains other non-programming related tools.
Games & Demos This contains some sample programs and games to play.
info & help This contains topics that give you help and information on
the ST/X environment and programming in Smalltalk.
snapshot This option takes a snapshot of your present ST/X environment
and asks for the name of the image file you wish to store the snapshot
in.
exit This option allows you to exit ST/X immediately or exit and save
a snapshot of the current environment.
The following sections describe most of these options in more detail.
The Browsers Options
The Browsers option in the Launcher menu gives you access to different
browsers or editors that let you read and manipulate classes, methods,
changes, senders, and implementors. The sub-options available are
* System Browser
* Class Hierarchy Browser
* Implementors
* Senders
* Changes Browser
* Directory Browser
Each of these sub-options will be discussed in detail in this section.
The System Browser
The standard System Browser contains five subviews:
* Class category list
* Class list
* Method category list
* Method list
* Code view
The System Browser is shown in Figure 34.3.
Figure 34.3. Within the ST/X system, classes are assigned to a
category. A category is simply an attribute used for grouping classes
to make them easier to handle. To select a class category, click on
the name of the category in the class category list. This is the
leftmost section of the top half of the System Browser. This will
display, in the class list subview, all classes belonging to that
category. The class list subview is the second section from the far
left of the system browser. You can also select one of two special
categories: * all *, which selects all classes and lists them
alphabetically; and * hierarchy *, which lists all classes in a tree
by inheritance.
If you select a class in the class list, all method categories for
that class will be displayed in the method category list, which is the
second section from the right in the top half of the System Browser.
Like class categories, method categories are simply for grouping
methods according to their function. When you select a method
category, all methods in that category are shown in the method list
view in the far right section of the browser. The special * all *
category will show all methods in alphabetical order. Selecting a
method from the method list will show the corresponding method's
source code in the code view which is the bottom half of the System
Browser.
The browser enables you to change either a class or its metaclass.
There are two toggle buttons, class and instance, in the same section
of the browser as the class list view. Instance, which is the default,
makes the changes affect the class. Selecting class makes the changes
affect the metaclass.A pop-up menu is available in each view by
pressing the middle or menu mouse button while the pointer is in that
view. The pop-up menu available in the class category view is shown in
Figure 34.4, and the purpose of each function is shown in Table 34.2.
Figure 34.4. The Class Category pop-up menu.
Table 34.2. Class Category pop-up menu functions.
Function Description
fileOut Saves all classes in the currently selected class category
into one source file named classCategory.st
fileOut each Saves all classes but puts each class into a separate
file called className.st
printOut Sends a printed representation of all classes selected to the
printer including the method source code
printOut protocol Sends a protocol-only representation of all classes
in the category to the printer without the method's source code
spawn Starts a class category browser without a class category list on
the currently selected class category
spawn class Starts a full class browser which allows you to edit all
code for the selected class in one view
update Re-scans all classes in the system and updates the lists shown
find class... Pops up a dialog box to enter the name of a class you
wish to search for and have displayed
new class category... Displays a dialog for the creation of a new
class category.
rename... Renames a category and changes the category attribute of all
classes in the currently selected class category
remove Removes all classes and subclasses in the current class
category
The class list pop-up menu appears when you press the menu mouse
button with the pointer in the class list view. The functions
available from this menu are shown in Figure 34.5 and are explained in
Table 34.3.
Figure 34.5. The Class List pop-up menu.
Table 34.3. Class List pop-up menu functions.
Function Description
fileOut Saves the source code of the currently selected class in a
file named className.st.
printOut Sends the source code of the currently selected class to the
printer.
printOut protocol Sends a protocol description of the currently
selected class to the printer. The output will contain the class
description, class comment, and the classes protocol and method
comments.
spawn Starts a class browser on the currently selected class.
spawn hierarchy Starts a browser on all subclasses of the currently
selected class.
hierarchy Shows the hierarchy of the currently selected class in the
code view.
definition Shows the class definition in the code view and allows you
to change the class definition.
comment Shows the class comment in the code view and allows you to
edit it.
class instvars Shows the class-instance-variables for the selected
class and allows you to edit them.
variable search Provides a search facility to find different variable
references and all methods referencing the searched-for variable.
new class Allows you to create a new class using as a template the
currently selected class.
new subclass Same as new class but it will create a subclass of the
currently selected class.
rename Changes the name of the currently selected class.
remove Removes the currently selected class and all of its subclasses.
The method category pop-up menu appears when you press the menu mouse
button while the pointer is in the method category view. The functions
available from this menu are shown in Figure 34.6 and explained in
Table 34.4.
Figure 34.6. The Method Category pop-up menu.
Table 34.4. Method Category pop-up menu functions.
Function Description
fileOut Saves the source code of the currently selected method
category in a file named className-category.st
printOut Sends the source code of the currently selected method
category to the printer
spawn Starts a method category browser on the currently selected
method category of the currently selected class
spawn category Starts a browser on all methods of the class which have
the same category as the currently selected one
find method here... Searches for the method that implements a
specified selector
find method... Searches in the class hierarchy for the first class
implementing the selector you specify in the dialog box
new category... Enables you to add a new category to the list
copy category... Enables you to copy all methods in a class category
to the currently selected class
create access methods Creates methods to access instance variables
rename... Renames the currently selected method category
remove Removes all methods in the currently selected class that are
members of the currently selected method category
The method list pop-up menu appears when you press the menu mouse
button while the pointer is in the method list view. The functions
available from this menu are shown in Figure 34.7 and explained in
Table 34.5.
Figure 34.7. The Method List pop-up menu.
Table 34.5. Method List pop-up menu functions.
Function Description
fileOut Saves the currently selected method in a file named
className-selector.st
printOut Sends the source code of the currently selected method to the
printer
spawn Starts a browser for editing this method
senders... Starts a new browser on all methods sending a specific
message
implementors... Starts a new browser on all methods implementing a
specific message
globals... Starts a new browser on all methods that are accessing a
global that is either a global variable or a symbol, as well as all
methods sending a corresponding message
local senders... Same as senders but limits the search to the current
class and its subclasses
local implementors... Same as implementors... but limits the search to
the current class and its subclasses
new method Enables you to create a new method from a template in the
code view
change category... Enables you to change the category of the selected
method
remove Removes the currently selected method
When you add or remove instance variables to or from a system class
description and accept (that is, save the changes), the system creates
a new class instead of changing the old one. The original class still
exists to give existing instances of the class a valid class even
though it is no longer accessible by name. After the change, you can
no longer edit the old class.
______________________________________________________________
NOTE: It is recommended that you don't change the definition of
system classes but only private ones. It is safer to use the copy
category function to copy an existing class and its methods to a
new class and modify the new class. This is especially important
for classes which are used by the system itself since changes can
lead to problems in the operation of the ST/X environment.
______________________________________________________________
The code view is the lower half of the System Browser. It is here that
you can modify the class or instance definitions as well as methods.
The pop-up menu for this area is the edit menu that appears in every
text editing view in ST/X. The functions in this menu are discussed in
the "Editing in Browsers" section of this chapter.
The Class Hierarchy Browser
When the Class Hierarchy Browser is selected, a dialog box appears
which asks for the name of class. If you enter a valid class, the
Class Hierarchy Browser appears for that class. This is the same as
the System Browser except there is no class category list since this
is for one specific class. The pop-up menus for each of the four
subviews are the same as in the System Browser.
Implementors
When the Implementors option is selected, a dialog box appears which
asks for a selector. A selector is the name of the type of operation a
message requests of its receiver.
If you enter a valid selector, an Implementors view will be displayed.
This view is similar to the one shown in Figure 34.8.
Figure 34.8. The Implementors view.
The Implementors view contains a list of the methods that implement
the method specified by the selector. The pop-up menu for the top half
of the Implementor view is the same as the pop-up menu for the method
list subview which was discussed in the "System Browser" section of
this chapter.
Senders
When the Senders option is selected, a dialog box appears that asks
for a selector. If you enter a valid selector, then a Senders view
will be displayed. This view is similar to the one shown in Figure
34.9.
Figure 34.9. Senders view.
The Senders view contains a list of the methods that send the selected
message. The pop-up menu for the top half of the Senders view is the
same as the pop-up menu for the method list subview which was
discussed in the "System Browser" section.
The Changes Browser
Each time you make a change to either the class hierarchy or to a
method, ST/X writes a record to a changes file. The Changes Browser
enables you to inspect and manipulate the changes file. There are two
subviews in the Changes Browser; the change list and the contents
view. The change list gives a list of all changes in chronological
order. A sample Changes Browser is shown in Figure 34.10.
Figure 34.10. The Changes Browser.
To display a change, select one of the changes from the change list.
The change browser then displays the contents of the change in the
contents view.
The pop-up menu for the change list has the functions described in
Table 34.6.
Table 34.6. The Change List pop-up menu.
Function Description
apply change Applies the currently selected change.
apply to end Applies all the changes from the currently selected
change to the end of the changes file.
apply all changes Applies all the changes in the file.
delete Deletes the currently selected change from the list.
delete to end Deletes all changes from the currently selected change
to the end of the file.
delete changes for Deletes all changes affecting the same class as the
currently selected this class change to the end of the changes file.
delete all changes Deletes all changes in the file for the same class
as the currently for this class selected change.
update Rereads the changes file.
compress Compresses the change list and removes multiple changes of a
method and leaves the most recent change compared to current.
compare with Compares a method's source code in a change with the
current current version version of the method and outputs a message in
the Transcript view.
make change a patch Appends the change to the end of the patches file
which will be run and automatically applied at ST/X startup.
save change a file Saves any changes made to the current file.
update sourcefile This function is not currently implemented.from
change
writeback changefile Writes the change list back to the changefile
changes file. All delete/compress operations performed in the Change
Browser will not affect the changes file unless this operation is
performed.
The Change Browser can be used to recover from a system crash by
re-applying all changes that were made after the last snapshot entry.
______________________________________________________________
NOTE: To control the size of the changes file, it is a good idea to
apply a compress periodically. This will remove all old changes for
a method leaving the newest one.
______________________________________________________________
Directory Browser
When you select the Directory Browser option, a browser with five
subviews is displayed. The top half of the browser displays the
current directory and all subdirectories and files contained in it. If
you select a directory, it is expanded in the next section to the
right across the top half of the browser. If you select a file, the
contents of the file are displayed in the lower half of the Browser.
The pop-up menu for the directory area has only two functions:
* up—Moves up to the directory above the one selected
* goto directory—Enables you to go to a specified directory
The content view has the same edit menu as all the other text editors
and is discussed in the "Editing in Browsers" section in this chapter.
A typical Directory Browser is shown in Figure 34.11.
Figure 34.11. The Directory Browser.
The Workspace Option
The Workspace option displays a view from which you can enter and
compile Smalltalk code. The Workspace is usually used as a testing
area or scratch pad when coding. You can use it to test your Smalltalk
code before building it into the code library using the System Browser
code view.
The File Browser Option
The File Browser gives you the ability to inspect and manipulate files
and directories. The File Browser is shown in Figure 34.12.
Figure 34.12. The File Browser.
It consists of four subviews that are described in Table 34.7.
Table 34.7. The File Browser subviews.
Subview Purpose
path-label field Shows the name of the current directory
file pattern field Allows a search pattern to be entered for choosing
files for the file list
file list Shows a list of file and directory names
contents view Shows the contents of a selected file
To inspect the contents of a file, double-click the left mouse button
on the name of the file in the file list. To change directories,
double-click on the directory name. Directory names are always shown
in the file list.
You can use the file pattern field to display the list of files
matching the specified pattern. The default is *, which shows all
files. The search pattern can be changed by moving the pointer to the
field, editing the pattern, and then pressing enter or choosing accept
from the file pattern pop-up menu.
As in the other browsers we have discussed, each subview has a pop-up
menu that is activated by the menu mouse button. The path-label pop-up
menu is shown in Figure 34.13.
Figure 34.13. The Path-Label pop-up menu.
The functions available in this menu are described in Table 34.8.
Table 34.8. The Path-Label pop-up menu functions.
Function Purpose
copy path Copies the current pathname into the cut and paste buffer
change directory... Opens a dialog box to enter the name of the
directory you wish to change to
change to home directory Changes the file list to your home directory
The file list pop-up menu is shown in Figure 34.14.
Figure 34.14. The File List pop-up menu.
The functions available in this menu are described in Table 34.9.
Table 34.9. The File List pop-up menu functions.
Function Purpose
spawn Starts another file browser on the current directory or the
directory selected in the file list.
get contents Shows the contents of the currently selected file in the
contents view.
show info Displays a view with type, size, access, and owner
information for the currently selected file or directory.
show full info Displays the same as above with more details such as
the last access, last modification date, and time.
fileIn Loads the selected file into the system by reading and
evaluating Smalltalk expressions from it.
update Rereads the directory and updates the file list.
execute unix command_ Allows execution of any UNIX command through a
pop-up box.
remove Removes the selected file(s) or directory(s).
rename... Renames the selected file.
display long list Shows file information in the file list. This option
toggles with display short list which is the default.
show all files Displays all the files including hidden files. This
option toggles with hide hidden files which is the default.
create directory... Creates a new directory.
create file... Creates a new file.
The pop-up menu for the contents view is the same edit menu as the
other text editors and is discussed in the "Editing in Browsers"
section of this chapter.
The Projects Option
The Projects option of the Launcher menu enables you to create a new
project or select a previously created project. When the new project
function is selected, a new project is automatically created for you
and the new project object appears on your screen. If you select the
select project function, a dialog box appears with a list of existing
projects from which to choose. Simply select a project and it will be
loaded in to the environment.
The Utilities Option
The Utilities option provides thirteen tools that assist you in
programming in the ST/X environment. Table 34.10 gives you a brief
description of each tool.
Table 34.10. The Utilities option.
Utility Description
Transcript Opens the Transcript view.
Window tree Displays a graphical tree representation of the window
hierarchy of all windows that are active or in wait state at the time
it was requested.
Class tree Displays a graphical tree representation of the class
hierarchy of the system.
Event monitor Displays a view that monitors events.
Process monitor Displays a view that gives information about all
currently active or waiting processes. This information changes as the
state of the processes change.
Memory monitor Displays a graph that tells you the present memory
usage and changes as the memory usage changes.
Memory usage Displays a table of the classes and the number of
instances of each, average size, bytes, and percentage of memory used
by each.
collect Garbage Runs a Generation Scavenge algorithm to collect short
term objects and destroy them. If an object survives long enough, it
is moved to an area of memory where it remains until the user requests
its collection.
collect Garbage & Same as Collect Garbage but also compresses
compress to recover space.
full screen hardcopy Takes a picture of the screen and asks you for a
name of a file with a .tiff extension in which to save the image.
screen area hardcopy Same as Fullscreen hardcopy but for only a
specific area of the screen.
view hardcopy Same as Fullscreen hardcopy but for one specific view
only.
ScreenSaver Enables you to choose from one of three different screen
savers to use in the ST/X environment.
The Goodies Option
The Goodies option of the Launcher menu provides a pull-right menu of
six different tools that are useful at any time, not just when you
program in Smalltalk. The Goodies are described in Table 34.11.
Table 34.11. The Goodies.
Tool Description
Clock Displays an analog clock in a square with a toggle for the
second hand.
Round Clock Same as the clock but it's round and remains visible when
it is minimized.
Directory View Displays a pictorial representation of files and
directories. A folder represents a directory and a document is a file.
Mail Tool A tool for managing electronic mail.
News Tool A repository for news, information and documents.
Draw Tool A fairly comprehensive tool for drawing diagrams, charts,
pictures, and so on.
The Games & Demo Option
Contained in the pull-right menu of this option are games for your
enjoyment and example applications that may be useful. The Games &
Demos option menu is shown in Figure 34.15.
Figure 34.15. The Games & Demos option menu.
Editing in Browsers
All views that show text allow the usual editing functions of that
text through a pop-up menu. The functions available in this menu are
described in Table 34.12.
Table 34.12. Editing functions.
Function Description
again Repeats the last edit.
copy Copies the selected text.
cut Cuts the selected text out of the file.
paste Pastes the text that was copied or cut prior to choosing the
paste option to the current position of the pointer.
doIt Evaluates the highlighted text.
printIt Prints a representation of the result of the evaluation at the
current cursor position.
inspectIt Invokes the Inspector view on the result.
accept Once you have completed editing, you must use this option to
save the changes to the file; otherwise, the changes will not be
written to the file.
search... Enables you to search for a specific string.
goto... Enables you to move to a specific location in the file.
font... Enables you to change the font of the file.
indent... Enables you to change the indenting of the file.
save as... Enables you to save the file under a different name.
print Prints the file.
To select or highlight text, press the left mouse button over the
first character and move the mouse (while pressing the mouse button)
to the end of the text you wish to select and then release the mouse
button. If you press the left mouse button again, the highlighting is
removed and you can select something else.
To scroll through the text, use the scroll bars on the left of the
view. By clicking the mouse below or above the thumb, the text scrolls
one page for every click. If you press the Shift key at the same time
as you click, the text scrolls to the position of the pointer in the
scroll bar. This is useful for scrolling rapidly through long
documents.
Using the Inspector
The Inspector enables you to inspect an object. It consists of two
subviews, one showing the names of the object's instance variables and
the other showing the value of the selected instance variable. You can
start an inspector by using the inspectIt function on the edit menu or
by sending one of the following messages to an object:
anObject inspect
or
anObject basicInspect
The basicInspect command will open a general inspector that shows
instance variables as they are physically present in the object. The
inspect command is redefined in some classes to open an inspector
showing the logical contents of the object.
Using the Debugger
The Debugger is displayed whenever an error occurs in your Smalltalk
code. It shows you where the error occurred and how the system got
there. The Debugger runs in one of three modes: normal, modal, and
inspecting.
When in normal mode and an error occurs in a process, which is not the
event handler process, the debugger will start up on top of the
erroneous process. This blocks all interaction with the affected
process and its views. Other views are still active and respond as
usual.
When an error occurs in the Smalltalk event handler process, the
debugger starts in modal mode. While a modal debugger is active you
cannot interact with any other view.
The inspecting mode can be entered from the ProcessMonitor by the
pop-up menu and allows inspection of the state of other processes. But
since the debugged process may continue to run, it is only possible to
inspect a snapshot of the affected process.
The Debugger contains four subviews:
* The Context Walkback List shows the context chain that led to the
error
* The Method Source View shows the method that caused the error
* The Receiver Inspector allows inspection of the receiver of the
selected message
* The Context Inspector provides information about the arguments and
local variables of this context.
The Debugger is shown in Figure 34.16.
Figure 34.16. The Debugger.
The functions that are common to each view appear as a set of buttons
below the context walkback list. These functions are described in
Table 34.13.
Table 34.13. The Debugger function buttons.
Button Description
terminate Terminates the erroneous process
abort Aborts the current activity if possible
return Continues execution as if the selected context returned
restart Continues execution by restarting the selected context
continue Continues execution
step (single step) Lets the process continue execution until the next
send is executed in the currently selected context
send (single send) Lets the process continue execution for one message
send
The walkback subview has a pop-up menu with the functions described in
Table 34.14.
Table 34.14. Walkback Subview pop-up menu function.
Function Description
exit smalltalk Leaves ST/X without saving an image
show more Shows 50 more contexts of the walk-back
breakpoints Not yet available
trace on/off Not yet available
trace step Not yet available
A miniDebugger is entered if an error occurs within the Debugger
itself. This is a line-by-line debugger that allows limited debugging
without the use of a graphical user interface. It is controlled by
entering commands in the Xterm window where ST/X was started. If you
type ? at the miniDebugger prompt, you will get a list of commands
that are available for use in this stripped down debugger.
Summary
This chapter introduced you to the Smalltalk environment that is
provided by the Smalltalk/X application. If you are interested in
learning how to program using Smalltalk and do not have access to one
of the commercial versions of Smalltalk, then Smalltalk/X is perfect
for you. Not only does Smalltalk/X come with all the tools and
programming aids that were talked about in this chapter, but it also
comes with many examples and some fairly complete documentation that
will make learning Smalltalk easier for you.
--
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※ 修改:．netiscpu 于 Jul 25 05:59:40 修改本文．[FROM: mtlab.hit.edu.cn]
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