Forum OpenACS Development: Re: creating a new xowiki class

In general there are several approaches to tailor xowiki's base classes. An important issue is in which scope you intend to modify the behavior:
- for all xowiki instances or for certain ones
- for all applications where a page of class ::xowiki::Page is used
- for all situations, where ::xowiki::WikiForm is used

Certainly, it is as well possible to define a new class. This will keep the information in the same tables as usual, but will create an additional table according to the OpenACS sub-typing conventions keeping essentially the revision_ids of the new class and additional attributes of the class (in your case none). I would not recommend to deviate from the OpenACS conventions to far. But i am not sure, that you want to define a new class for your application.

If you want to modify the behavior for a single "type of application", i would recommend to subtype the xowiki package (e.g. myapp) and to mixin the wanted behavior for every connection request to myapp. You can do this by creating a class ::myapp::Package with superclass ::xowiki::Package and add/remove the behavior each time a package instance is initialized/destroyed (provide methods "initialize" and "destroy"). The package s5 does a similar thing. In your case, you could mixin the wanted behavior for e.g. the WikiForm (don't forget to remove the mixin in the destroy method of the Package). The method "initialize" was added in april this year to xotcl-core.

Hope this helps
-gustaf neumann

This looks to me to complicated.

The question is how to characterize these "few cases". I assume for now, that the "few cases" can be characterized as a type of application, therefore subclassing the xowiki app (like in s5) looks appropriate. i would do the following way:

1) subclass xowiki::Package as ::myapp::Package
2) in mayapp-procs.tcl, define in addition to ::myapp::Package the class ::myapp::MyWikiForm with the intended methods (use "next" in the methods to chain to the default behaviour if necessary/intended)
3) in the method initialize of ::myapp::Package, make a "::xowiki::MyForm instmixin add ::myapp::MyWikiForm; next"
4) in the method destroy of ::myapp::Package, do a "::xowiki::MyForm instmixin delete ::myapp::MyWikiForm; next"

There is no duplication of code involved.

I did what you suggested and it worked, I managed to mixin the Forms and add the wanted behavior, but I had a few complications:

- If I restart the server, it loads my procs file first and throws an error because it needs some other definitions on the next files (not a big deal).
- To test my new app right now I changed the index.vuh so instead of call the initialize from ::xowiki::Package it calls ::myapp::Package but I need to leave it independent from the rest of the pages, I tried using another .vuh file inside another folder or using a .tcl file but it always says that "page" is not available. (the xowiki message if I want to create that page)

Any suggestions,

Thank you very much for your help Gustaf,

Thanks for the help Stefan,

I know the second part sounds confusing but is actually not that confusing.

The xowiki's index.vuh does this:

::xowiki::Package initialize -ad_doc {
} ...

and I changed it to do this:

::myapp::Package initialize -ad_doc {
} ...

So now when I call a xowiki/?edit-new=1 it actually initializes myapp and it works, but I can't leave the index.vuh file like this.

My question is how could I set a file to work the way I want, should I use a .vuh. I tried using a tcl file with that code but when it founds the part of the code:

::myapp::Package initialize -ad_doc {
} ...

it ignores the file.

right... as described in the tutorial section... :)

everything ok by now?

Everything worked out well, but for some reason I keep getting the same error about the loading packages.

I placed the line "::xo::db::require package xowiki" at the beginning of myapp-procs.tcl (the only procs file), I did it exactly the same way as the s5 package but it keeps failing.

Is there anything else I need to check for this ...

Thank you Gustaf,

what you added in that section is exactly what I did and it worked for me.