[Xotcl] Re: [Xotcl] Object mixin with passing init args ?

From: Zoran Vasiljevic <zoran_at_munich.com>
Date: Wed, 13 Dec 2000 06:15:16 -0500 (EST)

------Original Message------
From: Gustaf Neumann <Gustaf.Neumann_at_wu-wien.ac.at>
To: Zoran Vasiljevic <zoran_at_munich.com>
Sent: December 13, 2000 10:41:01 AM GMT
Subject: [Xotcl] RE: [Xotcl] Re: [Xotcl] Object mixin with passing init args
?


> from the implementation point of view this is not a big issue.
>however, from my experience, i should note that i switched from a
>style of "passing arguments to init" to the "-parameter style of
>configuring objects", which is in almost all cases the more
elegant
>solution.

<snip>

Yes. I must admit that your reasoning is correct. One gets wierd
constructs if thinking about all possible situations.

But, let me explain my issue. There may be another solution.

I have couple of classes impementing tree-like operations on
XML files and regular filesystems. Both classes share the same
abstract class, Tree (when I think of the Storage implementation in XOTcl
distro, then this case would be very similar).
Now, each of (Xml/Ufs) classes are mixed-in the general
Tree object. Each of them needs a different argument
pointing to a xml-file/file-directory where to hook on.

Consider ...

Class Tree ;# has abstract methods mostly
Class XmlTree -superclass Tree ;# implements above methods
Class UfsTree -superclass Tree ;# ...

XmlTree instproc init {xmlFile} {....}
UfsTree instproc init {rootDir} {....}

Tree t
t mixin XmlTree /path/to/xmlfile.xml ;# use the Xml driver
t mixin UfsTree /some/dir ;# switch to filesystem driver

Dang ! Showstopper, since I cannot pass arg to XmlTree/UfsTree.
Any suggestions ?


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