Re: debian/control: enhanced version dependencies?

[Steffen Möller <steffen_moeller@gmx.de>]

On 15/01/16 09:33, Harald Dunkel wrote:
> On 01/14/2016 10:11 AM, Andrey Rahmatullin wrote:
>> On Thu, Jan 14, 2016 at 09:35:31AM +0100, Harald Dunkel wrote:
>>> For running a local set of meta packages I would like to
>>> express package dependencies depending upon other packages
>>> installed, e.g.
>>>
>>> Package: xyz
>>> Version: all
>>> Depends: ${misc:Depends}
>>> 	, dbus (systemd >= 215)
>>>
>>> Hopefully you get the meaning. 
>> I'm not sure I do.
>>
>>> Package xyz could make sure
>>> that dbus is installed, if systemd is installed. (systemd
>>> version 215 itself just recommends dbus.)
>> What if systemd isn't installed? Nothing happens?
>>
> Thats what I was trying to express.
>
>>>
>>> Another example:
>>>
>>> Package: mykde
>>> Version: all
>>> Depends: ${misc:Depends}
>>> 	. kde-full
>>> 	, mykde1 (kde-full >= 5:66)
>>> 	, mykde2 (kde-full >= 5:77)
>>> 	, mykde3 (kde-full >= 5:84)
>>>
>>> Package mykde1
>>> :
>>> :
>> This is even less clear.
>>
> In this example mykde depends upon kde-full and a set of other
> packages, depending upon the version of kde-full.
>
> I am not proud of the syntax, either. Surely you have a better
> suggestion about how to express this kind of package dependencies.
>
The '|' character to express a condition is already taken,
and so are the parentheses.

How about some Perl-like post-annotation as in

Package: mykde
Version: all
Depends: ${misc:Depends}
	. kde-full
	, mykde1 if kde-full >= 5:66
	, mykde2 if kde-full >= 5:77
	, mykde3 if kde-full >= 5:84

This way you can mix the two semantics

Package: mykde
Version: all
Depends: ${misc:Depends}
	. kde-full
	, mykde1 (>= 4.99)if kde-full >= 5:66
	, mykde1 (>= 5.0) if kde-full >= 5:77

How long will it take until someone implements tic-tac-toe
with Debian package dependencies? Just kidding.

If the package maintainers get this right, then I
think these logics would indeed help to get Debian systems
leaner and possibly also more stable. But I primarily see
some beauty that intrigues me.

Steffen