[systemd-devel] Requires and After

[James Feeney]

On 1/1/19 8:33 PM, Reindl Harald wrote:
> "After" is a soft dependency, if that unit isn't enabled or don#t exist
> at all it don't matter
> 
> "Requires" is a hard dependency and it makes no sense not imply ordering

And then, what do you mean by "soft dependency" and "hard dependency"?  It sounds like you are calling an ordering dependency "soft" and an activation dependency "hard".

I'm sorry, I do not understand what you mean by "makes no sense not imply ordering".  Do you mean "to not imply ordering makes no sense"?  In which case, are you saying that "an activation dependency must imply an ordering"?  That would not be true.  Activating a unit does not automatically imply or require that that unit be activated or deactivated in any particular order relative to any other unit.

Did you also mean to say "If a unit is not active or does not exist then the ordering of that unit does not matter"?  Well, the "ordering" of a nonexistent unit would not have any meaning.

However there is also the case of an active unit that may become inactive, in addition to the case of an inactive unit that may become active.  While the order of activation or deactivation, relative to other units, of a unit that exists has meaning, that order may not, a priori, be of any importance or consequence.  But I would not go so far as to say that the order of activation of an inactive unit does not matter.  The order of activation of an inactive unit may actually be important, in which case, an ordering dependency can be specified.

So, I think that I am missing your point, with respect to "soft" and "hard" dependencies.  Maybe you could express your meaning in another way?