[gentoo-portage-dev] if (world file) then {no add to world when update pkg}

[Patrick Börjesson]

I just thought that if portage-ng is to rely on a world file just as
current portage, then one idea would be to not add the packages you
update manually with 'emerge -u <package name>' to it.
There was a thread in gentoo-user today which took up this matter when
someone asked for a way to update all the packages currently installed
on his machine. One method is to run 'emerge -Du `qpkg -I -nc`', but as
someone pointed out, this would add every single package you have on
your system to your world file (which I guess nobody wants) if you
didn't supply the --oneshot flag to emerge. I propose that the default
behaviour for portage-ng would be to check whether the package you're
trying to update is already installed on the system, else do nothing.
And if it's installed it shouldn't add the package to world after the
merging is completed (which it currently does). 
Would there be some negative sides of doing it this way? And if not, why
is this not default behaviour in current portage?
Feedback (in all its forms) appreciated.

Patrick Börjesson

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