Xotcl December 2005

xotcl@alice.wu.ac.at

2 participants
4 discussions

RE: [Xotcl] Is this a bug?
by Murr, Florian 13 Dec '05

13 Dec '05

Thanks a lot for your thorough explanation! I tend to think in "invariants" and I memorized that having a method specialized this way C instproc someMethod {args} { next } should leave my program invariant with respect to functionality. But this obviously has the exception of getter/setter methods. Regards, - Florian -----Original Message----- From: Gustaf Neumann [mailto:neumann@wu-wien.ac.at] Sent: Thursday, December 08, 2005 4:15 PM To: Murr, Florian Cc: xotcl(a)alice.wu-wien.ac.at Subject: Re: [Xotcl] Is this a bug? Murr, Florian schrieb: >Yes, you are right, I overload the setter/getter method and expected >naively that it just prints the puts-statement and works otherwise >unchanged. [Should have read the manual more properly, I guess :-)] > > for each parameter a method for getting and setting variables registered. This method is a "instparametercmd" implemented in C, which is very similar to the set method. This can be as well explained with the forwarder, which could be used to implement the *parametercmds Class C C instforward x %self set %proc now a method named x is defined, that calls "[self] set x" when issued. eg. C c1 c1 x 123 here "c1 set x 123" is called, or in the following line "c1 set x" is issued. puts [c1 x] This behavior is more or less identical to Class C C instparametercmd x or to Class C -parameter x therefore, the instparamtercmd is strictly speaking not needed, but predates instforward and is slightly faster, since everything is in C. The parameters do more, since they can be used to provide as well default values which are used during initialization of objects. anyhow, in all cases a method named "x" is defined. When you define an instproc named x Class C C instproc x args {...} you will overwrite the method "x", in a similar manner as you can overwrite any tcl command, e.g proc if args { ...} Therefore, there is no chance to do a next in these cases, because the class has now the new method (instproc) instead of the c-level implementation we had earlier. Furthermore "next" works only when methods are shadowed, when a same-named method is defined by a class/object earlier in the precedence order. This can be achieved e.g. via mixins or filters. therefore, in your example >X instproc y {args} { > puts "[self] y '$args'" > my instvar y > if {[llength $args]} { set y [lindex $args 0] } > next >} > > the "next" is not doing anything useful, you should replace the last line of your instproc by e.g. "return $y", such that .... [x1 y] ... works hope this explains, how this works... -gustaf neumann

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XOTcl 1.3.9 available
by Gustaf Neumann 09 Dec '05

09 Dec '05

Dear XOTcl community, I am pleased to annouce the availability of XOTcl 1.3.9. Major changes relative to 1.3.8 are: * Improved Functionality + new subcommand for self: [self args] return the full argument list of the current call + "<obj> info vars" does not trigger read traces on each variable anymore + Serializer: exportMethods accepts forwards/instforwards now as well + new switch -nocomplain for "mixin|instmixin|filter|instfilter delete" to avoid error messages when deleting entries not there (similar unset) + require automatically a namespace when a childobject is added + new command ::xotcl::__qualify: convert an relative name into an command name (exactly as create does it, ignoring namespaces from transparent interceptors) * Improved code quality: + fixing version numbers for package require + Upgraded TEA to 3.4 + updated rpm build (many thanks to Ildiko Schmidt and Alexander Bergolth) + fixed bug with error propagation when getter/setter methods are used for parameters (many thanks to Manfred Stelzhammer for pointing this out) 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

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RE: [Xotcl] Is this a bug?
by Murr, Florian 08 Dec '05

08 Dec '05

When I run the script, I get: ::x y 'y0' ::x y 'y1' ::x init '' ::x y '' expected 'y1', but got: '' Yes, you are right, I overload the setter/getter method and expected naively that it just prints the puts-statement and works otherwise unchanged. [Should have read the manual more properly, I guess :-)] I can achieve my desired result too, by doing something like: X instproc y {args} { puts "[self] y '$args'" my instvar y if {[llength $args]} { set y [lindex $args 0] } next } But I wanted to have an 'official' answer to this behaviour. Regards, - Florian -----Original Message----- From: Gustaf Neumann [mailto:neumann@wu-wien.ac.at] Sent: Thursday, December 08, 2005 12:43 PM To: Murr, Florian Cc: xotcl(a)alice.wu-wien.ac.at Subject: Re: [Xotcl] Is this a bug? Hmm, are you sure? the script you have sent does not produce the message you are indicating.... ~/scripts> set ::xotcl::version 1.3 ~/scripts> set ::xotcl::patchlevel .8 ~/scripts> Class X -parameter { > {y y0} >} ::X ~/scripts> X instproc init {args} { puts "[self] init '$args'"; next } ~/scripts> X instproc y {args} { > set x [next] > puts "[self] y '$args'" > set x >} ~/scripts> X create x -y y1 ::x y 'y0' ::x y 'y1' ::x init '' ::x ============================= however, most probably it is not doing what you might be expecting. your method y overwrites the setter method of parameter y, therefore in this example, not much happens in the next of method y. maybe you had in mind to overload the setter/getter method, which you can do e.g. with a mixin (see below) Class X -parameter { {y y0} } -instmixin [Class new -instproc y args { puts "[self] [self proc] $args" set x [next] puts "[self] [self proc] $args setter returns <$x>" return $x }] X create x -y y1 puts x.y=[x set y]

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Is this a bug?
by Murr, Florian 08 Dec '05

08 Dec '05

package require XOTcl 1.3.8 namespace import xotcl::* Class X -parameter { {y y0} } X instproc init {args} { puts "[self] init '$args'"; next } X instproc y {args} { set x [next] puts "[self] y '$args'" set x } X create x -y y1 puts "expected 'y1', but got: '[x y]'" regards, - Florian Murr

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Xotcl December 2005