Xotcl

xotcl@alice.wu.ac.at

2 participants
653 discussions

Deleting objects
by MichaelL＠frogware.com 12 May '03

12 May '03

Look at the following code, which is meant to be a stripped-down and simplified version of my real code: Class DatabaseMgr DatabaseMgr instproc openDatabase {} { Database [self]::db } Class Database Database instproc init {} { puts "init [self]" } Database instproc destroy {} { puts "destroy [self]" } DatabaseMgr dbmgr dbmgr openDatabase dbmgr::db info class dbmgr::db destroy dbmgr::db info class The second call to "info class" should fail but doesn't. That's because the object isn't actually destroyed. (In my real code the objects have dynamically generated names; I used the static names to simplify the example.) The above style is similar to the style of code used in xoRBAC (eg, factories & self-destruction) so I'd be surprised if it too wasn't leaking objects. After the above code run this code: dbmgr info class dbmgr destroy dbmgr info class Now both dbmgr and dbmgr::db are destroyed--but note that the "destructor" gets called twice at this point! By contrast, the following example (which also uses nested/aggregated objects) succeeds (which is to say that the second call to "info class" fails): Object instproc doSomethingAndDie {} {[self] destroy} set xxx [Object new] set yyy [Object new -childof $xxx] set zzz [Object new -childof $yyy] puts "[$yyy info class]" $yyy doSomethingAndDie puts "[$yyy info class]"

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Tcl party?
by Kristoffer Lawson 07 May '03

07 May '03

I've been running this idea about a Tcl party on c.l.t and I decided to post it here too, in case someone missed it. The plan would be to get a cool venue here in Finland and have a real proper code party (in the demoscene sense) for about 3 days. These are nothing like normal user meetings or conferences. The events are 24h/day (although naturally you can sleep if you want) and the focus is on the compos. Compos allow you to show off your skills, creativity and ideas to the audience and have them vote on the best for prizes. Some competition ideas: - Tcl game - Useless extension - Demo competition (multimedia presentation) - Real-time coding competition. - Obfuscated Tcl - ... In addition an important part is meeting and hanging out with people from all round. It's difficult to beat the feeling when people are crowded together, hacking away at some really cool ideas with the deadline looming... If the place was appropriate, and I think I could manage it, we could fry sausages and drink the odd beer, plus enjoy a good sauna and swim. Accommodation is free -- often people camp inside the party place -- but youc an stay in a hotel too if that's your preference. I haven't got much in the way of a positive response to this idea -- not quite sure why -- but at least 'Stonekeeper' from IRC described the idea as "very tempting", so I haven't quite given up yet. I myself am very excited by the idea so please, if this sounds at all like something you might be interested in, give me a shout so I don't give up hope entirely. / http://www.fishpool.com/~setok/

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Metakit db as storage
by Michael Schlenker 07 May '03

07 May '03

Hi, i looked at the persistence example and saw that there is no Metakit storage class yet. This would be a nice addidition especially if using XOTcl with tclkit (that has metakit already embedded). What has to be done to implement metakit storage? Just provide the few abstract instprocs from /library/store/Storage.xotcl ? Michael Schlenker

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Help with singleton design pattern
by Michael A. Cleverly 23 Apr '03

23 Apr '03

As I'm starting to learn XOTcl, I decided to try and implement a singleton design pattern as an educational exercise. Here is what I've come up with see below). I'd appreciate help understanding why my filterguard registration does not work as I'd expect it to. (I'd also appreciate feedback on style, or if my comments indicate a misunderstanding of what the code actually does, etc.) Thanks again for all the help. Michael #!/bin/sh # -*- tcl -*- \ exec tclsh $0 ${1+"$@"} package require Tcl 8.4 package require XOTcl 1.0 namespace import -force xotcl::* Class Singleton Singleton instproc singletonCreateFilter args { # Despite adding a filterguard (see below) for some reason # the "C foo" below would fail because a singleton instance of # class C exists ("::singletonCreateFilter" ?!??) if we don't also # check to make sure [self calledproc] == create here. # # I don't understand why ... if {[self calledproc] != "create"} { return [next] } [self class] instvar singletons set obj [lindex $args 0] set class [self] # if the object name isn't a fully qualified name make it so if {![string match ::* $obj]} { set obj [namespace parent]::$obj } # don't throw an error if we're recreating the same object if {[info exists singletons($class)] && [string equal $singletons($class) $obj] == 0} { error "Can't instantiate \"$obj\" of singleton class\ \"$class\"; \"$singletons($class)\" already instantiated" } set singletons($class) $obj next } Singleton instproc singletonDestroyFilter args { [self class] instvar singletons set class [my info class] ;# equiv of [self] info class # if other objects existed before Singleton registerClass # was called, and those objects are deleted, we don't care if {$singletons($class) == [self]} { unset singletons($class) } next } Singleton proc registerClass class { my instvar singletons my instvar registered # make sure we're dealing with a class if {[my isclass $class] == 0} { error "\"$class\" isn't a class;\ hence, can't make it a singleton class." } # Don't "double register" a class if {[info exists registered] && [lsearch -exact $registered $class] != -1} then return # We need to mixin to the object to filter the obj creation # We need to mixin to the class to filter obj destruction $class mixinappend [self] $class instmixinappend [self] $class filterappend singletonCreateFilter $class filterguard singletonCreateFilter \ {[self calledproc] == "create"} $class instfilterappend singletonDestroyFilter $class instfilterguard singletonDestroyFilter \ {[self calledproc] == "destroy"} lappend registered $class } Singleton proc create args { # doesn't make sense to instantiate objects of the singleton class error "Can't instantiate an object of \"[self]\";\ use \"[self] registerClass className\" instead." } Class C # just a quick sanity check to make sure our filter doesn't # keep us from defining instance procs or using them C instproc datetime {} { clock format [clock seconds] } Singleton registerClass C # don't expect/don't want [C foo] to fail C foo puts [foo datetime] # We expect/want [C bar] to fail C bar

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info classchildren leads to a segfault
by Michael A. Cleverly 17 Apr '03

17 Apr '03

Since every class is also an object, its possible to define both procs & instprocs for it. The instprocs define methods that objects of this class will have, while the proc (as I understand it) proc would define a method on the class object, but not for objects of the class. (Yes?) However, during my interactive playing around trying different things I've found that as soon as I define a proc on the class object any subsequent use of [info classchildren] leads to a segfault. $ tclsh % package require XOTcl 1.0 % namespace import xotcl::* % Class C ::C % C info classchildren % C proc foo args {} % C info classchildren Segmentation fault Is it better to avoid defining procs on the class object, or am I misunderstanding when & where to use [info classchildren]? Michael

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Static member functions?
by Michael A. Cleverly 17 Apr '03

17 Apr '03

(Disclaimer: I'm quite new to XOTcl & I have read the tutorial a couple times but maybe not enough. :-) What's the XOTcl idiom/way for a static member variable (what snit, the only other OO Tcl package/extension I've used, would call a "type variable")? Contrived example: if I had a "Chapters" class, I'd like to have a single variable, accessible by all instances of the class, that kept track of the "current" chapter. Suggestions? Michael

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Multi threaded web-server in XOTcl
by Gustaf Neumann 17 Apr '03

17 Apr '03

Fellow XOTcl-community, maybe, someone finds the following code useful. The attached file implements a simple multi threaded Webserver in XOTcl that uses Zoran's the wonderful tcl thread library 2.5. It is about 150 lines of code and supports conditional requests (if-modified-since). best regards -gustaf neumann

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XOTclIDE Version 0.42
by Artur Trzewik 12 Apr '03

12 Apr '03

Hallo! New release of XOTclIDE 0.42 is available on http://www.xdobry.de/xotclIDE Changes: 1) Converage Analysis Browser - The tool is based on method call tracker and It can be useful to proof the coverage of unit test. 2) Global variables inspector - help to inspect global variables (also in namespaces). Helpful to inspect pure-tcl applications 3) Wizard for importing tcl procs into XOTclIDE components from interpreter. 4) some small changes (bugs, inkonsequences) By the way. XOTclIDE will be presented on 4. European Tcl/Tk User Meeting (31.05.2003) http://www.t-ide.com/tcl2003e.html Artur Trzewik

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Delegation
by Kristoffer Lawson 08 Apr '03

08 Apr '03

I've been looking at Snit recently and there are definite benefits from being able to use delegation -- it allows the combination of objects from Snit with other object-like commands in Tcl (which there are definitely quite a few of). I believe XOTcl could possibly benefit from this extra style. Naturally it would be really easy to do with filters and the unknown mechanism (as I was thinking of doing with Tk at one point), but perhaps there could be some use for an "official" approach to that. I'm not sure if this would be seen as polluting XOTcl or making it overly complex (I still believe in keeping things as simple as possible). Possibly it could be provided as a pure-XOTcl capability. Just a thought. / http://www.fishpool.com/~setok/

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XOTcl 1.0.2 available
by Gustaf Neumann 21 Mar '03

21 Mar '03

Dear XOTcl community XOTcl 1.0.2 is available! Below is the full announcement text! best regards -gustaf neumann ======================================================================== Announcing XOTcl 1.0.2 ********************** WHAT IS XOTCL? XOTcl is an object-oriented extension of Tcl that was derived from OTcl. In short, XOTcl tries to provide a highly flexible, reflective, component-based, and object-oriented environment. It integrates language support for high level concepts which are not found in other languages, with reasonable performance. It prevails the Tcl programming style and the dynamic/introspective nature of the language, rather than introducing other language's styles and rigidness (such as C++) into Tcl. CHANGES relative to 1.0.1 are: - fixes: * fixes for copying/moving objects to same name * works out of the box with AOL-server 4.0 (no patch for AOL-server needed) * various small fixes and code cleanup * new directory structure (no nested version numbers) * improved object and class serializer - new functionality and improvements: * new method "ismixin": Test whether the argument is a mixin or instmixin of the object. * new method "hasclass": Test whether the argument is either a mixin or instmixin of the object or if it is on the class hierarchy of the object. This method combines the functionalities of istype and ismixin. * arguments of configure methods can start now with a leading "-" without ambiguity. In previous versions Class C -parameter {name counter} C c1 -name -x -counter 123 the configuration of c1 was interpreted as follows method argc name 0 x 0 counter 1 Starting with XOTcl 1.0.2 arguments can be protected by putting it into a list: C c1 [list -name -x] -counter 123 which is interpreted as follows: method argc name 1 counter 1 For more details, please consult the ChangeLog 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 -- Univ.Prof. Dr.Gustaf Neumann Abteilung für Wirtschaftsinformatik WU-Wien, Augasse 2-6, 1090 Wien

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