Linux
by Rick McMullin
IN THIS CHAPTER
- What Is SmallTalk/X?
- How to Install SmallTalk/X
- Invoking SmallTalk/X
- Getting Around in ST/X
- The Browsers Option
- The Workspace Option
- The File Browser Option
- The Projects Option
- The Utilities Option
- The Goodies Option
- The Games & Demos Option
- Editing in Browsers
- Using the Inspector
- n Using the Debugger
This chapter describes the 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
- How to invoke SmallTalk/X
- How to get 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.
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 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.
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:
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/libX11.so.3.1.0 /usr/lib/libX11.so.3
ln /usr/i486-linuxaout/lib/libXt.so.3.1.0 /usr/lib/libXt.so.3
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.
You invoke SmallTalk/X by typing
smalltalk
in an Xterm window. 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
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 36.1.
Figure 36.1.The Transcript view.
The Transcript is the console where relevant systems information is shown. The
Launcher menu is shown in Figure 36.2.
The Launcher allows access to the tools you will need to program your application.
Table 36.1 gives the options available from the Launcher and a brief description
of each.
Figure 36.2. The Launcher menu.
Table 36.1. 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. |
| File Browser |
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 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 suboptions available are
- System Browser
- Class Hierarchy Browser
- Implementors
- Senders
- Changes Browser
- Directory Browser
Each of these suboptions will be discussed in detail in this section.
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 36.3.
Figure 36.3. The System Browser.
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 36.4, and
the purpose of each function is shown in Table 36.2.
Figure 36.4. The class category pop-up menu.
Table 36.2. 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 |
Rescans 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 want to search for and have
displayed |
| 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 36.5 and are explained in Table 36.3.
Figure 36.5. The class list pop-up menu.
Table 36.3. 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 36.6 and explained in Table 36.4.
Figure 36.6. The method category pop-up menu.
Table 36.4. 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 36.7 and explained in Table 36.5.
Figure 36.7. The method list pop- up menu.
Table 36.5. 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 |
| 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.
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.
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 36.8.
Figure 36.8. 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 earlier in
the section "The System Browser."
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 36.9.
Figure 36.9. 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 section "The System 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 36.10.
Figure 36.10. 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 36.6.
Table 36.6. 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 to end |
change to the end of the changes file. |
| delete all changes |
Deletes all changes in the file for the same class as the currently 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. |
| version |
Compares a method's source code in a change with the current version of the method
and outputs a message in the Transcript view. |
| make a change patch |
Appends the change to the end of the patches file which will be run and automatically
applied at ST/X startup. |
| update sourcefile from change |
This function is not currently implemented. |
| writeback |
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 reapplying 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.
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, later in this chapter. A typical
Directory Browser is shown in Figure 36.11.
Figure 36.11. The Directory Browser.
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 gives you the ability to inspect and manipulate files and directories.
The File Browser is shown in Figure 36.12.
Figure 36.12. The File Browser.
It consists of four subviews that are described in Table 36.7.
Table 36.7. 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
36.13.
Figure 36.13. The path-label pop-up menu.
The functions available in this menu are described in Table 36.8.
Table 36.8. 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 want to change to |
| change to home-dir |
Changes the file list to your home directory |
The file list pop-up menu is shown in Figure 36.14.
The functions available in this menu are described in Table 36.9.
Figure 36.14. The file list pop-up menu.
Table 36.9. 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 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 provides 13 tools that assist you in programming in the ST/X
environment. Table 36.10 gives you a brief description of each tool.
Table 36.10. The Utilities option tools.
| 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 & compress |
Same as Collect Garbage but also compresses to recover space. |
| Fullscreen 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 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 36.11.
Table 36.11. 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. |
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 36.15.
Figure 36.15. The Games & Demos option
menu.
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 36.12.
Table 36.12. 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. |
| 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. |
| 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. |
| 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.
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.
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 36.16.
Figure 36.16. 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 36.13.
Table 36.13. The debugger function buttons.
| Button |
Description |
| continue |
Continues execution |
| terminate |
Terminates the erroneous process |
| abort |
Aborts the current activity if possible |
| 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 |
| return |
Continues execution as if the selected context returned |
| restart |
Continues execution by restarting the selected context |
The Walkback subview has a pop-up menu with the functions described in Table 36.14.
Table 36.14. 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 Walkback |
| 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.
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.
Contact
reference@developer.com with questions or comments.
Copyright 1998
EarthWeb Inc., All rights reserved.
PLEASE READ THE ACCEPTABLE USAGE STATEMENT.
Copyright 1998 Macmillan Computer Publishing. All rights reserved.
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