[Xotcl] XOTcl 1.6.0 issue with "Object info class"

Edmond Ho edmondho at gmail.com
Mon Mar 10 18:06:12 CET 2008


Hello Gustaf,

Thanks for your reply!

The recommended way to check, if an object is of a certain
> type (is a direct/indirect instance of a certain class) is to
> use "istype".
>

I replaced all of my calls to "Object info class ?pattern?" to "Object
istype ?pattern?" and it works well. Out of curiosity, is the "istype"
method new to 1.6.0?


The old interface matches only with the
> superclass elements, when pattern is specified.
> There are essentially two options to proceed:
>
> (a) "info class ?pattern?" could be fixed to match
> with the current class and the superclasses, but then
> it should return always empty, when the pattern
> does not match, as it is now in accordance to
> other cases, where ?pattern? is used.
>
> (b) It is as well possible to remove the ?pattern?
> argument from "info class", since there is as well
> istype. Note that there is as well
> "info precedence ?pattern?", which returns the
> resolution order including mixins and superclasses.
>
> approach (a) makes it easy to query the classes either
> with or without mixins,  but to get the full list,
> one should use "[f info class] info superclass -closure",
> or we implement as well a "info class -closure".
>
> Or in the case (b) "info precedence" could get
> an option to list only intrinsic classes (classes
> which are no mixins). One can use a single
> method to get a full or partial list, and one can
> use ?pattern? to filter the list in a uniform way.
>
> Opinions?


To me, option (b) seems clearer. Type checking is simplified to the use of
"istype", while "info" is focused on more advanced introspection. However,
I'm new to XOTcl, so I may not be thinking ahead to interaction with the
advanced features. I'm sure you guys will make the best decision!

The only thing I'll ask for here is the updated documentation on the
website. I also think that there should be documentation for each major
version of XOTcl on the website, so that it's clearer as what the
differences are between versions. Just my two cents.

Thanks again!

Cheers,
Edmond
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