GNU Smalltalk

https://www.gnu.org/software/smalltalk/manual/html_node/
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### Swazoo configuration file example

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Swazoo.html

Example configuration file for Swazoo that defines a site named 'hello' on port 8080 with a composite resource and a HelloWorldResource.

```smalltalk
<Site name: 'hello'; port: 8080>
 <CompositeResource uriPattern: ''/''>
  <HelloWorldResource uriPattern: ''hello.html''>
 </CompositeResource>
</Site>

```

--------------------------------

### Example deposit and spend operations

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Moving-money-around.html

Shows example usage of the deposit: and spend: methods on an account object 'a'. Deposits 125 and 20, then spends 10.

```smalltalk
   a deposit: 125
   a deposit: 20
   a spend: 10

```

--------------------------------

### Start GNU Smalltalk with gst command

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Starting-Smalltalk.html

Run 'gst' in a terminal to start GNU Smalltalk. The system loads and displays a startup banner.

```shell
   **$** gst

```

--------------------------------

### package.xml example for DBD-SQLite

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Packages.html

Example package.xml file showing the structure for a GNU Smalltalk package, including name, namespace, prerequisites, module, test subpackage, filein list, and extra files.

```xml
<package>
  <name>DBD-SQLite</name>
  <namespace>DBI.SQLite</namespace>

  <!-- _The prereq tag identifies packages that
       must be loaded before this one._ -->
  <prereq>DBI</prereq>

  <!-- _The module tag loads a dynamic shared object
       and calls the gst_initModule function in it.  Modules
       can register functions so that Smalltalk code can call them,
       and can interact with or manipulate Smalltalk objects._ -->
  <module>dbd-sqlite3</module>

  <!-- _A separate subpackage can be defined for testing purposes.
       The SUnit package is implicitly made a prerequisite of the
       testing subpackage, and the default value of namespace
       is the one given for the outer package._ -->
  <test>
    <!-- _Specifies a testing script that gst-sunit (see SUnit)
         will run in order to test the package.  If this is specified outside
         the testing subpackage, the package should list SUnit among
         the prerequisites._ -->
    <sunit>DBI.SQLite.SQLiteTestSuite</sunit>
    <filein>SQLiteTests.st</filein>
  </test>

  <!-- _The filein tag identifies files that
       compose this package and that should be loaded in the
       image in this order._ -->
  <filein>SQLite.st</filein>
  <filein>Connection.st</filein>
  <filein>ResultSet.st</filein>
  <filein>Statement.st</filein>
  <filein>Row.st</filein>
  <filein>ColumnInfo.st</filein>
  <filein>Table.st</filein>
  <filein>TableColumnInfo.st</filein>

  <!-- _The file tag identifies extra files that
       compose this package’s distribution._ -->
  <file>SQLiteTests.st</file>
  <file>ChangeLog</file>
</package>

```

--------------------------------

### Start Swazoo with gst-load

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Swazoo.html

Starts the Swazoo web server using the gst-load command. The ARG parameter can be 'swazoodemo' or a configuration file path on first use.

```shell
$ gst-load --start_[=ARG]_ Swazoo

```

--------------------------------

### Specify arguments for open(2)

Source: https://www.gnu.org/software/smalltalk/manual/html_node/C-callout.html

Example of the args: array for a call to open(2), specifying a string and two int arguments.

```smalltalk
args: #(#string #int #int)

```

--------------------------------

### Start VisualGST browser with gst-browser

Source: https://www.gnu.org/software/smalltalk/manual/html_node/GUI.html

Command to start the GNU Smalltalk GTK browser (VisualGST). It loads requested packages and then displays a launcher window with all basic tools.

```shell
    gst-browser

```

--------------------------------

### Start Seaside server (foreground and daemon)

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Seaside.html

Two commands to start Seaside: one runs the server in the foreground, the other runs it as a daemon controllable via gst-remote. Both serve pages at http://localhost:8080/seaside.

```shell
$ gst-load -I seaside.im --start Seaside
$ gst-remote -I seaside.im --daemon --start=Seaside

```

--------------------------------

### Send the 'new' message to the Account class

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Defining-methods.html

Command line example that sends the 'new' message to the Account class, triggering the method defined above.

```smalltalk
   Account new

```

--------------------------------

### Download and install a package from URL

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Packages.html

Use gst-package with a URL to a package.xml file or use the short form --download to fetch a package from GNU Smalltalk's web site. The two commands are equivalent.

```shell
    gst-package http://smalltalk.gnu.org/project/Iliad/package.xml
    gst-package --download Iliad

```

--------------------------------

### GNU Smalltalk startup banner output

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Starting-Smalltalk.html

Expected output after starting GNU Smalltalk: a banner and the interactive prompt 'st>'. Exit by typing control-D on an empty line.

```text
     GNU Smalltalk ready

     st>

```

--------------------------------

### Start GNU Smalltalk with -V flag

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Saying-hello.html

Start GNU Smalltalk with the -V flag to enable printing of performance statistics about the underlying Smalltalk engine.

```bash
   **$** gst -V

```

--------------------------------

### package.xml entry for a module

Source: https://www.gnu.org/software/smalltalk/manual/html_node/External-modules.html

Example package file for a module, showing the <module> tag and the filein entries for the Smalltalk source files. This is used when packaging bindings as .star files.

```xml
<package>
  <name>Digest</name>
  <filein>digest.st</filein>
  <filein>md5.st</filein>
  <filein>sha1.st</filein>
  <module>digest</module>

  <test>
   <sunit>MD5Test SHA1Test</sunit>
   <filein>mdtests.st</filein>
  </test>
</package>

```

--------------------------------

### Recursive retry example (before)

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Handling-exceptions.html

Shows a recursive approach using sig return: to retry, which increases stack height. The source recommends replacing this with the retry example.

```smalltalk
  frobnicate: n [
    ^[do some stuff with n]
        on: SomeError
        do: [:sig | sig return: (self frobnicate: n + 1)]
    ]

```

--------------------------------

### Smalltalk message precedence examples

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows two message expressions and their parenthesized equivalents to illustrate default precedence.

```smalltalk
myvar at: 2 + 3 put: 4
mybool ifTrue: [ ^ 2 / 4 roundup ]
```

```smalltalk
(myvar at: (2 + 3) put: (4))
(mybool ifTrue: ([ ^ (2 / (4 roundup)) ]))
```

--------------------------------

### Install a package with gst-package

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Packages.html

Run gst-package with a path to a package.xml file to create a .star archive in the current image directory. By default, the package is placed in the system-wide package directory; use --target-directory to change the destination.

```shell
    gst-package path/to/package.xml

```

--------------------------------

### Smalltalk binary message example and parse

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows a binary message expression and its parenthesized parse.

```smalltalk
1 + 2 - 3 / 4
```

```smalltalk
(((1 + 2) - 3) / 4)
```

--------------------------------

### Load packages with PackageLoader fileInPackages: and fileInPackage:

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Packages.html

Use PackageLoader to load multiple packages at once or a single package. The example loads DBD-MySQL and DBD-SQLite, then loads Sockets.

```smalltalk
    PackageLoader fileInPackages: #('DBD-MySQL' 'DBD-SQLite').
    PackageLoader fileInPackage: 'Sockets'.

```

--------------------------------

### Variable binding syntax for a global

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Namespaces.html

Shows the variable binding syntax that returns the Association for a particular global, equivalent to the absolute pathname example.

```smalltalk
#{Smalltalk.Tasks.MyTask} value
```

--------------------------------

### Use Checking instance to deposit and write checks in Smalltalk

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Writing-checks.html

Shows a typical session: create a Checking instance, deposit 250, fill the checkbook with 50 checks starting at number 100, write a check for 32, and inspect the object.

```smalltalk
   c := Checking new
   c deposit: 250
   c newChecks: 100 count: 50
   c writeCheck: 32
   c
```

--------------------------------

### Start Swazoo in background with gst-remote

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Swazoo.html

Loads Swazoo into a background GNU Smalltalk virtual machine using gst-remote. ARG can be 'swazoodemo' or a configuration file path on first use.

```shell
$ gst-remote --start=Swazoo_[:ARG]_

```

--------------------------------

### Symbol examples

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows three symbol constants: a simple identifier, a binary selector, and a keyword selector. Symbols are used to represent method names.

```smalltalk
   #hello
   #+
   #at:put:

```

--------------------------------

### C struct declaration for audio_prinfo and audio_info

Source: https://www.gnu.org/software/smalltalk/manual/html_node/C-data-types.html

Example C struct definitions for audio_prinfo and audio_info, used as a reference for the Smalltalk CStruct equivalent.

```c
struct audio_prinfo {
    unsigned    channels;
    unsigned    precision;
    unsigned    encoding;
    unsigned    gain;
    unsigned    port;
    unsigned    _xxx[4];
    unsigned    samples;
    unsigned    eof;
    unsigned char       pause;
    unsigned char       error;
    unsigned char       waiting;
    unsigned char       _ccc[3];
    unsigned char       open;
    unsigned char       active;
};

struct audio_info {
    audio_prinfo_t      play;
    audio_prinfo_t      record;
    unsigned    monitor_gain;
    unsigned    _yyy[4];
};

```

--------------------------------

### Initialize GNU Smalltalk from C (gst-tool.c snippet)

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Using-Smalltalk.html

Simplified main() from gst-tool.c showing how to initialize GNU Smalltalk as an extension library. Calls gst_set_var, gst_smalltalk_args, gst_set_executable_path, gst_initialize, gst_process_file, and gst_invoke_hook. gst_initialize may take 0.1 to 3-4 seconds to check/rebuild the image; pass a valid image file to avoid the check. The result of gst_init_smalltalk is 0 for success, anything else is an error code.

```c
int main(argc, argv)
int     argc;
char    **argv;
{
  gst_set_var (GST_VERBOSITY, 1);
  gst_smalltalk_args (argc - 1, argv + 1);
  gst_set_executable_path (argv[0]);
  result = gst_initialize ("kernel-dir", "image-file", GST_NO_TTY);
  if (result != 0)
    exit (result < 0 ? 1 : result);

  if (!gst_process_file ("source-file", GST_DIR_KERNEL_SYSTEM))
    perror ("gst: couldn't load `source-file'");

  gst_invoke_hook (GST_ABOUT_TO_QUIT);
  exit (0);
}

```

--------------------------------

### Array constant example

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows an array constant with mixed literal types: integers, a string, a character, a symbol, and a radix number. The assignment to variable 'a' is part of the example.

```smalltalk
   a := #(1 2 'Hi' $x #Hello 4 16r3F)

```

--------------------------------

### Prepare a source tree with gst-package

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Packages.html

Run gst-package --prepare with paths to package.xml files to create a skeleton GNU style source tree, including configure.ac and Makefile.am. This supports standard Makefile targets like make install and make dist.

```shell
    gst-package --prepare path1/package.xml path2/package.xml

```

--------------------------------

### Smalltalk unary message example

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows a unary message cascade on a literal number.

```smalltalk
1234 printNl printNl printNl
```

--------------------------------

### Create and run a TestSuite with TestSuite named:

Source: https://www.gnu.org/software/smalltalk/manual/html_node/SUnit.html

Creates a TestSuite named 'Money', adds two test cases (MoneyTestCase selectors #testAdd and #testSubtract), and runs the suite. The result is a TestResult object that records failures, errors, and the run time.

```smalltalk
(TestSuite named: 'Money')
    add: (MoneyTestCase selector: #testAdd);
    add: (MoneyTestCase selector: #testSubtract);
    run

```

--------------------------------

### #onOccurrencesOfRegex:do:

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Regular-expressions.html

Invokes a block on every successful match of the regular expression in the receiver. Each search starts at the end of the previous match.

```APIDOC
## #onOccurrencesOfRegex:do:

### Description
Iterates over all non-overlapping matches of the regular expression in the receiver, invoking the given block for each match. The block receives a RegexResults object for each match.

### Method
#onOccurrencesOfRegex:do:

### Parameters
- **aRegex** (String or Regex) - Required - The regular expression to search for.
- **aBlock** (Block) - Required - A block that receives a RegexResults object for each match.

### Returns
- **void** - No return value.

### Example
```smalltalk
stream contents onOccurrencesOfRegex: '\w+' do: [:each | each match printNl]
```
```

--------------------------------

### Array pointer declaration in CStruct

Source: https://www.gnu.org/software/smalltalk/manual/html_node/C-data-types.html

Syntax for declaring an array pointer of a given size. Maps to char *example[size] in C.

```smalltalk
        (#example (#array #string size))

```

--------------------------------

### Explore the class hierarchy with superclass

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Why-is-_0023new-there_003f_0021_003f.html

Interactive Smalltalk session showing the superclass chain from Set up to Object, ending with nil. Use this to verify the class hierarchy in the image.

```smalltalk
    st> `Set superclass!`
    HashedCollection

    st> `HashedCollection superclass!`
    Collection

    st> `Collection superclass!`
    Object

    st> `Object superclass!`
    nil

```

--------------------------------

### Create an Account instance

Source: https://www.gnu.org/software/smalltalk/manual/html_node/A-look-at-our-object.html

Creates a new Account object and assigns it to a Smalltalk variable named 'a'. The expression 'Account new' returns a new Account, and the assignment also prints the object.

```smalltalk
   a := Account new

```

--------------------------------

### Retrieve values from a dictionary

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Dictionaries.html

Uses `at:` to retrieve values by key. The example shows retrieving the value for key 1 and for key 'Two'.

```smalltalk
   y at: 1
   y at: 'Two'

```

--------------------------------

### ByteArray constant example

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-syntax.html

Shows a ByteArray constant with integer elements, including radix numbers. Elements are constrained to integers between 0 and 255.

```smalltalk
   a := #[1 2 34 16r8F 26r3H 253]

```

--------------------------------

### Invoke GNU Smalltalk with flags and files

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Invocation.html

Shows the general command line syntax for invoking the GNU Smalltalk virtual machine. The flags and file arguments are optional; if no file is given, standard input is read with an 'st>' prompt when it is a terminal.

```shell
gst [ flags … ] [ file … ]
```

--------------------------------

### Makefile.am for building a module with Automake and Libtool

Source: https://www.gnu.org/software/smalltalk/manual/html_node/External-modules.html

Shows how to build a dynamic module using GNU Automake and Libtool. The LDFLAGS include -module and -no-undefined, and the source files are listed in SOURCES.

```makefile
gstmodule_LTLIBRARIES = libdigest.la
libdigest_la_LDFLAGS = -module -no-undefined _... more flags ..._
libdigest_la_SOURCES = _... your source files ..._

```

--------------------------------

### Add two integers with +

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Doing-math.html

Sends the + message to the integer 9 with argument 7, which answers the value 16. This is an example of arithmetic messages for integers.

```smalltalk
   9 + 7

```

--------------------------------

### Class definition syntax

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Syntax.html

Shows the syntax for creating a new class, including instance variables, pragmas, message patterns, and class variables.

```smalltalk
superclass-name `subclass:` new-class-name `[`
`|` instance variables `|`
pragmas
message-pattern-1 `[` statements `]`
message-pattern-2 `[` statements `]`
…
class-variable-1 `:=` expression`. `
class-variable-2 `:=` expression`. `
…
`]`

```

--------------------------------

### Invoke standard output stream directly

Source: https://www.gnu.org/software/smalltalk/manual/html_node/The-output-stream.html

Use this to write to the standard output stream directly. The first line prints 'Hello, world' to stdout, and the second line inspects the stdout stream.

```smalltalk
   'Hello, world' printOn: stdout
   stdout inspect

```

--------------------------------

### Stop Swazoo background server with gst-remote

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Swazoo.html

Stops a background Swazoo server using gst-remote. ARG can have the same meanings as for starting, except it cannot be a configuration file.

```shell
$ gst-remote --stop=Swazoo_[:ARG]_

```

--------------------------------

### Define Account class and instance methods in a single declaration

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Instance-methods.html

Shows a single-declaration alternative to using `extend`, defining the Account class with an instance variable `balance`, a class method `new` that initializes a new instance, and the instance method `init`. The `new` method uses `super new` and calls `r init` before returning the new object.

```smalltalk
Object subclass: Account [
    | balance |
    <comment:
        'I represent a place to deposit and withdraw money'>
    Account class >> new [
        <category: 'instance creation'>
        | r |
        r := super new.
        r init.
        ^r
    ]
    init [
        <category: 'initialization'>
        balance := 0
    ]
]

```

--------------------------------

### Inspect an Interval object

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Looking-at-objects.html

Sends `inspect` to an Interval object to display its instance variables. The output shows the start, stop, step, and contents array.

```smalltalk
   x := Interval from: 1 to: 5.
   x inspect

```

```output
   An instance of Interval
   start: 1
   stop: 5
   step: 1
   contents: [
       [1]: 1
       [2]: 2
       [3]: 3
       [4]: 4
       [5]: 5
   ]

```

--------------------------------

### Define an instance method with Account extend

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Instance-methods.html

Defines the `init` instance method for Account objects using the `extend` syntax. The method sets the instance variable `balance` to zero and does not return a value; Smalltalk defaults the return value to the object currently executing.

```smalltalk
Account extend [
    init [
        <category: 'initialization'>
        balance := 0
    ]
]

```

--------------------------------

### Parse configuration file lines with =~ and ifMatched:

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Regular-expressions.html

Uses the `=~` operator to match a line against a regex, and `ifMatched:` to access register groups. The example reads a file 'myapp.conf', stores key-value pairs in a LookupTable, and prints the table. The regex captures a word key and a value consisting of space-separated words.

```smalltalk
| file config |
config := LookupTable new.
file := (File name: 'myapp.conf') readStream.
file linesDo: [:line |
    (line =~ '(\w+)\s*=\s*((?: ?\w+)+)') ifMatched: [:match |
        config at: (match at: 1) put: (match at: 2)]].
file close.
config printNl.

```

--------------------------------

### asyncCall

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Other-C-functions.html

Sets up the interpreter to call a function as soon as the next message send is executed. Accepts a function pointer and an OOP (or NULL).

```APIDOC
## asyncCall

### Description
Sets up the interpreter to call the given function as soon as the next message send is executed. The function pointer must be a valid C function, and the OOP argument can be NULL but not an arbitrary pointer.

### Function Signature
void asyncCall(void (*)(OOP), OOP)

### Parameters
- **function pointer** (function pointer) - Required - The function to be called.
- **OOP** (OOP) - Required - The OOP argument to pass to the function, or NULL.

### Remarks
This function is thread-safe, along with asyncSignal and asyncSignalAndUnregister.
```

--------------------------------

### Smalltalk example: #ensure: and exception handler

Source: https://www.gnu.org/software/smalltalk/manual/html_node/Handler-stack-unwinding-caveat.html

Shows that in Smalltalk, the #ensure: block is not executed until the handler's #return: is invoked, so the transcript prints '42' then '24'.

```smalltalk
| n |
n := 42.
[[self error: 'error'] ensure: [n := 24]]
    on: Error
    do: [:sig | n printNl. sig return].
n printNl.

```

--------------------------------

### Running a test case

Source: https://www.gnu.org/software/smalltalk/manual/html_node/SUnit.html

Creates an instance of a TestCase subclass with the selector of the testing method and sends run to it. If it runs to completion, the test worked; a walkback indicates something went wrong.

```smalltalk
(SetTestCase selector: #testAdd) run

```
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