Compatibility between KDE 3 and KDE 4

Thiago Macieira thiago at
Tue Jun 7 12:28:24 BST 2005

Martijn Klingens wrote:
>Do you want KDE 3 DCOP to be upwards compatible to KDE 4 IPC or just
> allow KDE 3 apps to work in a KDE 4 environment? The subtle difference
> is that in the latter case we only need to provide the existing
> interfaces without caring about new ones that might appear.
>Without talking about possible ways to reach either goals (as I said,
>first collect the issues), I myself would opt for the latter.

And I think we can do better. Without going into the "how", it's difficult 
to decide.

But from the ideas we got last time we discussed D-BUS here, I'd say that 
it is feasible to give full access to the new environment, not just a 
compatibility area. In other words, I think the conclusion was:

- KDE4 apps will speak D-BUS natively
- KDE3 apps can talk to KDE4 apps normally, and vice-versa
- KDE3 apps cannot talk to non-KDE D-BUS apps
- non-KDE D-BUS apps can send simple messages that are to be relayed into 

This would, of course, require that we have a dcopserver. In fact, if we 
want to support DCOP at all, we'll need dcopserver.

>> Just add the "4" to the name, if the layout of those files is not
>> compatible with the KDE3 apps.
>For clarity, the name of the containing folder or the actual filename?

I don't think /etc4 exists, so /etc/kde4rc :-)

In fact, I think we should read both files, as well as both environment 
variables. The "4" version should override, if found, similarly to what 
XFree86 did to XF86Config vs XF86Config-4.

> In the latter case e.g. kdeglobals would become kde4globals in $KDEHOME
> as well. (Hmm, might not be a bad idea...)

  Thiago Macieira  -  thiago (AT) macieira (DOT) info
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