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<title>Migration Guide from XOTcl 1 to XOTcl 2</title>
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<h1>Introduction</h1>
... general text, maybe partly from slides/paper ....
<h2>Supporting XOTcl 1 in XOTcl 2</h2>
<p> In general, the XOTcl 2 environment supports multiple object
systems concurrently. Effectively, every object system has different
base classes for creating both, objects and classes. Therefore, the
object systems can have different different interfaces and names of
builtin methods. Currently, XOTcl 2 supports primarily XOTcl 1 and
XOTcl 2 (XOTcl 1 provides about twice as many predefined builtin
methods). </p>
<p> The support for multiple object systems can be used to load XOTcl
1 and XOTcl 2 scripts into the same interpreter. This makes migration
from XOTcl 1 to XOTcl 2 easier. The XOTcl environment provides the
predefined command ::xotcl::use to make switching between these
objects systems convenient. The following example script shows a single
script defining classes of XOTcl 1 and 2:<p>
<pre>
package require XOTcl
namespace eval mypackage {
<i># Some definitions for XOTcl 1</i>
::xotcl::use xotcl1
Class C1
C1 instproc foo {} {puts "hello world"}
<i># Some definitions for XOTcl 2</i>
::xotcl::use xotcl2
Class create C2 {
.method foo {} {puts "hello world"}
}
}
</pre>
<p> "Switching" effectively means the load some libraries if needed
and to import either the XOTcl 1 or XOTcl 2 base classes as
<code>Object</code> and <code>Class</code> into the current namespace.
If the import is not wanted, just use <code>package require</code> to
load the necessary pieces.
</p>
<h1>XOTcl 1 Idioms in XOTcl 2</h1>
<h2>Defining Objects and Classes</h2>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code>Class <i>ClassName</i></code></td>
<td><code>Class create <i>ClassName</i></code></td>
</tr>
<tr>
<td><code>Object <i>ObjectName</i></code></td>
<td><code>Object create <i>ObjectName</i></code></td>
</tr>
<tr>
<td><code>::xotcl::Class <i>ClassName</i></code></td>
<td><code>::xotcl2::Class create <i>ClassName</i></code></td>
</tr>
<tr>
<td><code>::xotcl::Object <i>ObjectName</i></code></td>
<td><code>::xotcl2::Object create <i>ObjectName</i></code></td>
</tr>
</table>
<h2>Defining Methods</h2>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code>Class <i>C</i><br>
<i>C</i> instproc <i>foo args</i> {...}<br>
<i>C</i> proc <i>bar args</i> {...}<br>
</code></td>
<td><code>Class create <i>C</i> {<br>
.method <i>foo args</i> {...}<br>
.object method <i>bar args</i> {...}<br>
}<br></code><hr>
<code>Class create <i>C</i><br>
<i>C</i> method <i>foo args</i> {...}<br>
<i>C</i> object method <i>bar args</i> {...}<br>
</code></td>
</tr>
<tr>
<td><code>Object <i>o</i><br>
<i>o</i> set <i>x 1</i><br>
<i>o</i> proc <i>foo args</i> {...}<br>
</code></td>
<td><code>Object create <i>o</i> {<br>
set .<i>x 1</i><br>
.method <i>foo args</i> {...}<br>
}<br></code><hr>
<code>Object create <i>o</i><br>
<i>o</i> eval {set <i>.x 1</i>}</i><br>
<i># ::xotcl::setinstvar o x 1</i><br>
<i>o</i> method <i>foo args</i> {...}<br>
</code></td>
</tr>
</table>
<h2>Resolvers</h2>
XOTcl 2 defines Tcl resolvers for method and variable names to refer
to object specific behavior. Withing method bodies these resolver
treat names staring with a dot "." specially. If one wants to refer to
a name starting with a "." (e.g. the name of a Tcl function starts
with a dot), the dot has to be duplicated, or one has to use the
usual namespace prefix "::" to refer to a namespaced entity. Note that
the XOTcl 2 resolver is used in the XOTcl 1 environment as well.
<h2>Invoking Methods</h2>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code>Class <i>C</i><br>
<i>C</i> instproc <i>foo args</i> {...}<br>
<i>C</i> instproc <i>bar args</i> {<br>
my <i>foo 1 2 3</i> ;# invoke own method<br>
<i>o baz</i> ;# invoke others method<br>
}<br>
Object <i>o</i><br>
<i>o</i> proc <i>baz</i> {} {...}<br>
</code></td>
<td><code>Class create <i>C</i> {<br>
.method <i>foo args</i> {...}<br>
.method <i>bar args</i> {<br>
.<i>foo 1 2 3</i> ;# invoke own method<br>
<i>o baz</i> ;# invoke others method<br>
}<br>
}</br>
Object create <i>o</i> {<br>
.method <i>baz</i> {} {...}<br>
}</br>
</code></td>
</tr>
</table>
<h2>Accessing Instance Variables from Method Bodies</h2>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code>Class <i>C</i><br>
<i>C</i> instproc <i>foo args</i> {<br>
<i># method scoped variable a</i><br>
set a 1 <br>
<i># instance variable b</i><br>
my instvar b<br>
set b 2<br>
<i># global variable/namespaced variable c</i><br>
set ::c 3<br>
}<br>
</code></td>
<td><code>Class create <i>C</i> {<br>
.method <i>foo args</i> {...}<br>
<i># method scoped variable a</i><br>
set a 1 <br>
<i># instance variable b</i><br>
set .b 2<br>
<i># global variable/namespaced variable c</i><br>
set ::c 3<br>
}<br>
}<br>
</code></td>
</tr>
<tr>
<td><code>my set <i>varname value</i></code></td>
<td><code>set .<i>varname value</i></code></td>
</tr>
<tr>
<td><code>set <i>newVar</i> [my set <i>otherVar</i>]</code></td>
<td><code>set <i>newVar</i> [set <i>.otherVar</i>]</code><br><hr>
<code>set <i>newVar</i> ${.otherVar}</i></code><br>
</td>
</tr>
<tr>
<td><code>my instvar <i>newVar</i><br>
set <i>newVar value</i> </code>
</td>
<td><code>set <i>.newVar value</i></td>
</tr>
<tr>
<td><code>my exists <i>varname</i></code></td>
<td><code>info .<i>varname</i></code></td>
</tr>
</table>
<h2>Accessing Instance Variables of other Objects</h2>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> set <i>varname value</i></code></td>
<td><code><i>obj</i> eval [list set <i>.varname value</i>]</code></td>
</tr>
<tr>
<td><code>set <i>newVar</i> [<i>obj</i> set <i>otherVar</i>]</code></td>
<td><code>set <i>newVar</i> [<i>obj</i> eval {set <i>.otherVar</i>}]</code><br>
</td>
</tr>
<tr>
<td><code><i>obj</i> instvar <i>newVar</i><br>
set <i>newVar value</i> </code>
</td>
<td><code>::xotcl::importvar <i>obj newVar</i><br>
set <i>newVar value</i></td>
</tr>
<tr>
<td><code><i>obj</i> exists <i>varname</i></code></td>
<td><code><i>obj</i> eval {info exists <i>.varname</i>}</code></td>
</tr>
</table>
<h2>Object Parameters</h2>
<h2>Method Parameters</h2>
<h2>Introspection</h2>
<h4>List methods defined by objects</h4>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> info commands <i>?pattern?</i></code></td>
<td><code><i>obj</i> info methods <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info parametercmd <i>?pattern?</i></code></td>
<td><code><i>obj</i> info methods -methodtype setter <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info procs <i>?pattern?</i></code></td>
<td><code><i>obj</i> info methods -methodtype scripted <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info methods -methodtype alias <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info methods -methodtype forwarder <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info methods -methodtype object <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info methods -callprotection <i>public|protected ...</i></code></td>
</tr>
</table>
<h4>List methods defined by classes</h4>
<table>
<tr>
<td><code><i>cls</i> info instcommands <i>?pattern?</i></code></td>
<td><code><i>cls</i> info methods <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instparametercmd <i>?pattern?</i></code></td>
<td><code><i>cls</i> info methods -methodtype setter <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instprocs <i>?pattern?</i></code></td>
<td><code><i>cls</i> info methods -methodtype scripted <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info methods -methodtype alias <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info methods -methodtype forwarder <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info methods -methodtype object <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info methods -callprotection <i>public|protected ...</i></code></td>
</tr>
</table>
<h4>List class object specific methods</h4>
<table>
<tr>
<td><code><i>cls</i> info commands <i>?pattern?</i></code></td>
<td><code><i>cls</i> object info methods <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info parametercmd <i>?pattern?</i></code></td>
<td><code><i>cls</i> object info methods -methodtype setter <i>?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info procs <i>?pattern?</i></code></td>
<td><code><i>cls</i> object info methods -methodtype scripted <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> object info methods -methodtype alias <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> object info methods -methodtype forwarder <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> object info methods -methodtype object <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> object info methods -callprotection <i>public|protected ...</i></code></td>
</tr>
</table>
<h4>List callable methods</h4>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> info methods <i>?pattern?</i></code></td>
<td><code><i>obj</i> info callable <i>?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i># list only application specific methods</i></code><br>
<code><i>obj</i> info callable -application</code></td>
</tr>
</table>
<h4>List object/class where some method is defined</h4>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> procsearch <i>methodName</i></code></td>
<td><code><i>obj</i> info callable -which <i>methodName</i></code></td>
</tr>
</table>
<h4>List definition of scripted methods defined by classes</h4>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>cls</i> info instbody <i>methodName</i></code></td>
<td><code><i>cls</i> info method body <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instargs <i>methodName</i></code></td>
<td><code><i>cls</i> info method args <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instnonposargs <i>methodName</i></code></td>
<td><code><i>cls</i> info method parameter <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instdefault <i>methodName</i></code></td>
<td><code><i>cls</i> info method parameter <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instpre <i>methodName</i></code></td>
<td><code><i>cls</i> info method precondition <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instpost <i>methodName</i></code></td>
<td><code><i>cls</i> info method postcondition <i>methodName</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info method definition <i>methodName</i></code></td>
</tr>
</table>
<h4>List definition of scripted object specific methods</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> info body <i>methodName</i></code></td>
<td><code><i>obj</i> info method body <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info args <i>methodName</i></code></td>
<td><code><i>obj</i> info method args <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info nonposargs <i>methodName</i></code></td>
<td><code><i>obj</i> info method parameter <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info default <i>methodName</i></code></td>
<td><code><i>obj</i> info method parameter <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info pre <i>methodName</i></code></td>
<td><code><i>obj</i> info method precondition <i>methodName</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info post <i>methodName</i></code></td>
<td><code><i>obj</i> info method postcondition <i>methodName</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info method definition <i>methodName</i></code></td>
</tr>
</table>
<p>For definition of class object specific methods, use modifier
<code>object</code> as shown in examples above.
</p>
<h4>List filter or mixins</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> info filter <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>obj</i> info filter <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info filter <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>cls</i> object info filter <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instfilter <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>cls</i> info filter <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info mixin <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>obj</i> info mixin <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info mixin <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>cls</i> object info mixin <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instmixin <i>?-order? ?-guards? ?pattern?</i></code></td>
<td><code><i>cls</i> info mixin <i>?-order? ?-guards? ?pattern?</i></code></td>
</tr>
</table>
<h4>List definition of methods defined by aliases, setters or forwarders</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info method definition <i>methodName</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls ?object?</i> info method definition <i>methodName</i></code></td>
</tr>
</table>
<h4>List fully qualified name of method</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info method name <i>methodName</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls ?object?</i> info method name <i>methodName</i></code></td>
</tr>
</table>
<h4>List type of a method</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>obj</i> info method type <i>methodName</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls ?object?</i> info method type <i>methodName</i></code></td>
</tr>
</table>
<h4>List the scope of mixin classes</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>cls</i> info mixinof <i>?-closure? ?pattern?</i></code></td>
<td><code><i>cls</i> info mixinof -scope object <i>?-closure? ?pattern?</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instmixinof <i>?-closure? ?pattern?</i></code></td>
<td><code><i>cls</i> info mixinof -scope class <i>?-closure? ?pattern?</i></code></td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code><i>cls</i> info mixinof -scope all <i>?-closure? ?pattern?</i></code></td>
</tr>
</table>
<h4>Check properties of object and classes</h4>
<table>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> istype <i>sometype</i></code></td>
<td>
<code>::xotcl::is <i>obj</i> type <i>sometype</i></code><br>
<hr>
<code><i>obj</i> info is type <i>sometype</i></code>
</td>
</tr>
<tr>
<td><code><i>obj</i> ismixin <i>cls</i></code></td>
<td>
<code>::xotcl::is <i>obj</i> mixin <i>cls</i></code><br>
<hr>
<code><i>obj</i> info is mixin <i>cls</i></code>
</td>
</tr>
<tr>
<td><code><i>obj</i> isclass <i>?cls?</i></code></td>
<td>
<code>::xotcl::is <i>obj|cls</i> class</code><br>
<hr>
<code><i>obj</i> info is class</code>
</td>
</tr>
<tr>
<td><code><i>obj</i> ismetaclass <i>cls</i></code></td>
<td><code>::xotcl::is <i>obj|cls</i> metaclass</code>
<hr>
<code><i>obj</i> info is metaclass</code>
</td>
</tr>
<tr>
<td><i>n.a.</i></td>
<td><code>::xotcl::is <i>cls</i> baseclass</code>
<hr>
<code><i>cls</i> info is baseclass</code>
</td>
</tr>
<tr>
<td><code><i>obj</i> isobject <i>obj2</i></code></td>
<td><code>::xotcl::is <i>obj|obj2</i> object</code>
<hr>
<code><i>obj</i> info is object</code>
</td>
</tr>
</table>
<h2>Predefined Methods</h2>
<h2>Dispatch, Aliases, etc.</h2>
<h2>Assertions</h2>
<table border=1>
<tr><th>XOTcl 1</th><th>XOTcl 2</th></tr>
<tr>
<td><code><i>obj</i> check <i>checkptions</i></code></td>
<td><code>::xotcl::assertion <i>obj</i> check <i>checkptions</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info check</code></td>
<td><code>::xotcl::assertion <i>obj</i> check</code></td>
</tr>
<tr>
<td><code><i>obj</i> invar <i>conditions</i></code></td>
<td><code>::xotcl::assertion <i>obj</i> object-invar <i>conditions</i></code></td>
</tr>
<tr>
<td><code><i>obj</i> info invar</code></td>
<td><code>::xotcl::assertion <i>obj</i> object-invar</code></td>
</tr>
<tr>
<td><code><i>cls</i> instinvar <i>conditions</i></code></td>
<td><code>::xotcl::assertion <i>cls</i> class-invar <i>conditions</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info instinvar</code></td>
<td><code>::xotcl::assertion <i>cls</i> class-invar</code></td>
</tr>
<tr>
<td><code><i>cls</i> invar <i>conditions</i></code></td>
<td><code>::xotcl::assertion <i>cls</i> object-invar <i>conditions</i></code></td>
</tr>
<tr>
<td><code><i>cls</i> info invar</code></td>
<td><code>::xotcl::assertion <i>cls</i> object-invar</code></td>
</tr
</table>
<h2>Method Protection</h2>
<h2>Incompatibilities</h2>
<h3>Namespace resolvers</h3>
<p>The XOTcl 2 namespace resolvers are use as well when XOTcl 1 is used
within XOTcl 2.
</p>
<h3>Stronger Checking</h3>
<p>XOTcl 2 performs stronger checking than XOTcl 1. The requiredness
of slots in XOTcl 1 was just a comment, while XOTcl 2 enforces it.
</p>
<h3>Different results</h3>
<ul>
<li><code>[self next]</code> returns <br>
instead of "proc" and "instproc" => "method"<br>
instead of "parametercmd" and "instparametercmd" => "setter"<br>
instead of "instforward" => "forward"<br>
instead of "instcmd" => "cmd".<br>
The modifier "object" is added when needed.
</li>
<li><code>[self filterreg]</code> returns <br>
instead of "instforward" => "forward"<br>
The modifier "object" is added when needed.
</li>
</ul>
<h3>Exit handlers</h3>
<p>
The exit hander interface changed from a method of
<code>::xotcl::Object</code> into procs in the <code>::xotcl</code>
namespace. XOTcl 2 provides now:
<pre>
::xotcl::setExitHandler script
::xotcl::getExitHandler
::xotcl::unsetExitHandler
</pre>
<hr>
<address></address>
<!-- hhmts start --> Last modified: Tue Jan 12 11:35:29 CET 2010 <!-- hhmts end -->
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