ANNOUNCE: XOTcl 1.5.0 available
GN
*************************
Dear Tcl Community. We are pleased to announce the availability of
XOTcl 1.5.0.
Major changes relative to 1.4.0 are:
* Improved Functionality
+ The C-level implementation of XOTcl creates now the basic
classes ::xotcl::Object and ::xotcl::Class completely without
any methods. All predefined methods are now registered from
the initialization script-code (predefined.xotcl) via the new
command
::xotcl::alias <class>|<obj> <methodName> \
?-objscope? ?-per-object? <cmdName>
which is used for registering predefined Tcl commands as
methods. These aliases are like zero cost forwarders, since
they lookup the function pointer from the commands and used
these in the methods.
This change makes it possible to register the same command
on different classes (with maybe different names), such that
for example the predefined set method of ::xotcl::Object can
be replaced with a different method and the set method can
be registered on some other classes (maybe some application
classes).
This change makes it as well quite easy to develop some
other object oriented languages based on the XOTcl
framework, since all methods can be rearrange from the Tcl
layer .
+ Slots
A slot is a meta-object that manages property-changes of
objects. A property is either an attribute or a role of an
relation.
In a nutshell, a slot has among other attributes
- a name (which it used to access it),
- a domain (object or class on which it can be used) , and
- can be multivalued or not
Every slot defines a uniform interface to access its
content. So has for example, every multivalued slot a
method "add" to add a value to the list of values and a
method "remove" to remove it again.
We distinguish between system slots (predefined slots like
class, superclass, mixin, instmixin, filter, instfilter) and
application slots (e.g. attributes of classes).
System Slots
========
System slots are predefined slots defining e.g. some relations
between classes, or between objects and classes.
The predefined system slots are:
- superclass: every class in XOTcl has one or more
superclasses. The name of this slot is "superclass", the
domain is "::xotcl::Class", the slot is multivalued. One
object might have multiple superclasses.
- class: every object has a class; therefore, the domain of
the slot is "::xotcl::Class", the property is not
multivalued.
- mixin: every object in XOTcl can have one or more mixin
classes. The name of this slot is "mixin", the domain is
"::xotcl::Object", the slot is multivalued.
- instmixin: same as above, but the domain is
"::xotcl::Class"
- filter, instfilter: similar to "mixin" and "instmixin"
Every slot can be used set and query the property from its
domain. The syntax for setting values is
<object> <property> newValue
and for getting its values is
set x [<object> <property>]
Every multivalued slot has as well a method "add" and "remove"
Examples for using the system slot "mixin"
Object o; Class M; class N
o mixin ::M ;# replacing the per-object mixins of o with M
o mixin add ::N ;# add N to the front of the mixin list
o mixin delete ::M ;# delete M from the mixin list
puts [o mixin] ;# query the current mixin list
Attribute Slots
=========
Attribute slots are used to manage the setting and querying
of instance variables. We define now a person with three
attributes,"name", "salary" and "projects".
Class Person -slots {
Attribute name
Attribute salary -default 0
Attribute projects -default {} -multivalued true
}
Examples for using the slots are
Person p1 -name "Joe"
p1 projects add project1
Some additional features of the slots are:
- Support for value checking for
* primitive types (all types from "string is", like
integer, boolean, ...)
* instances of Classes (e.g. value must be an instance
of Person)
* custom value checkers
* uniform interface for single and multi-valued slots
- Support for lazy initialization (e.g. when costly
commands (like SQL) are used to initialize instance
variables, not all variables are used for each object)
- more experimental low level functionality, like
* initcmd (executed, whenever the variable is read
the first time)
* valuecmd (executed, whenever the variable is read)
* valuechangedcmd (executed, whenever the
variable is altered)
For more details, see
http://media.wu-wien.ac.at/doc/tutorial.html#slots
+ Re-implementation of the method "parameter" based on slots.
All forms except
... -parameter {name1 {name2 default2}} ...
(I.e. pure accessor parameters and parameters with
defaults) are deprecated, since slots are the much more
powerful and orthogonal construct.
The old C-based parameter support based on "parameterclass"
is deprecated. It is still in the C-code (the method
"parameter" is redefined in predefined.xotcl). If someone
urgently needs it, please remove the parameter instproc from
predefined for the time being, and write an email to me, in
case you really need it). The C code for parameter will be
removed in the next release.
+ Improved introspection though the procsearch method. This
method reports now in its second argument not only
[inst]proc but as well [inst]forward, [inst]parametercmd and
[inst]cmd (the latter for methods implemented in C.
* Improved introspection through "info"
- new subcommand "info slots"
- implemented backwards bug-compatible "info parameter",
deprecated
+ Improved serializer
- better handling of cyclical dependencies, when mixins are
involved
- fix for namespace handling to make the XOTcl communication
library classes working with the aolserver (thanks to
Stefan Sobernig for pointing this out)
- Now other ::xotcl::* objects can be included in the
aolserver blueprint (e.g. non positional argument
handlers)
- handling of slot dependencies
- more convenient calling of the serializer: Method
"serialize" for Object is defined when the package
xotcl::serializer is loaded.
+ Improved forwarding commands
- New option for the argument substitution. When the
argument list of the forward command contains
"%argclindex {a b c}", then depending of the number of
arguments at invocation "a", "b" or "c" is
substituted. If more arguments are used at the invocation
of the forwarder than values are contained in the list
after %argclindex, an error is generated.
- New options for forwarder:
* The option -earlybinding can be used to look up the
function pointer of the called Tcl command at
definition time of the forwarder instead of invocation
time. This option should only be used for calling
C-implemented Tcl commands)
* The option -verbose prints the substituted command in
the forwarder prior to invocation.
+ New snit-like utility functions:
- ::xotcl::myvar varName: return the fully qualified
variable name of the specified variable.
- ::xotcl::myproc methodName ?args?: call an xotcl method
without the need of using "[list [self] methodName ...]"
Both commands are namespace exported
+ added "subst" to the set of Tcl imported methods (like
e.g. incr, append, ...). One can do now:
% Object o
::o
% o subst {I am [self]}
I am ::o
+ added new method for ::xotcl::Object named "contains": This
method is essentially a value added back-port of the OpenACS
version. It allows to create a nested object structure with
little syntactic overhead. See tutorial or language
reference for more details.
* Improved code quality:
+ fixed a bug with nonpositional arguments, some positional
arguments and "args"
+ fixed a bug in nonpositional arguments when called without
arguments
+ tested with Tcl 8.4.13 and 8.5a4
+ improved error messages in connection with nonpositional
arguments
+ fixed a bug in the xotcl trace module (many thanks to jima for
reporting)
+ fixed a namespace bug in ::xotcl::package require in
connection with xotclide (many thanks to Bill Paulsen and
Artur Trzewik for identifying the problem and suggesting a
fix)
+ improved documentation (e.g. new sections added, some sections
deleted, spelling improved, in total 8 pages longer)
+ fixed documentation bugs (many thanks for Kristoffer for
reporting)
+ more regression tests added
For more details about the changes, please consult the ChangeLog and
documentation.
MORE INFO
General and more detailed information about XOTcl and its components
can be found at http://www.xotcl.org
Best regards,
Gustaf Neumann
Uwe Zdun
Robert Hicks
I have it on my Windows box now...but I wonder if it will build for OSX
out of the tarball?
Robert
jima
Just a question about slots.
I understand that when you add values to a multivalued slot the values
are prepended to the list and that this is so because it goes well with
mixins behaviour.
But I find strange this prepend thing. If I have an attribute of a
class that is a list of things I might want the list to be added new
elements by its end instead of by its beginning. Could this be changed
arbitrarily for multivalued slots?
Thanks.
jima
jima
Class ::AttL -superclass Attribute
::AttL instproc add {
obj
prop
value
{pos "end"}
} {
next $obj $prop $value $pos
}
jima
GN
Robert Hicks wrote:
> I have it on my Windows box now...but I wonder if it will build for OSX
> out of the tarball?
yes, i am doing most of the development on Mac OS X now. One needs the
developer toolkit (for gcc ...), and then the usual "configure; make;
sudo make install". Depending on the installation, one might like to
use the option --with-tcl for configure (tcl, xotcl are included in mac
os developer toolkit, use --with-tcl to avoid version mismatch).
-gustaf neumann
GN
jima wrote:
> I found a way:
>
> Class ::AttL -superclass Attribute
Exactly; one can use this class as well as a instmixin for Attribute.