[Bioc-devel] Depending vs. Importing?

Oleg Sklyar osklyar at ebi.ac.uk
Sun Jul 9 13:24:01 CEST 2006

Without going to your particular example, the main difference as I see
it, is that developers using import can still make the packages usable
in case a dependency is broken.

Suppose your package is intended for some complex analysis (for which it
does not need anything) and can additionally produce some fancy
graphical output of the analysis if it loads a dependency. Now if this
dependency is broken (missing, cannot be compiled etc) - with depends
your package will fail to install; with import the package developer
could have tested for the result and implemented some simple plots if
the dependency is broken - but the package would still work for the

If however, the package fails to work completely when it cannot import
something, then such import should go into depends to allow for the
error during the installation time.

Generally, you do not want to make a package totally non-functional if 1
of 10 dependencies fails, therefore it is reasonable to use import for
lesser important features of the package.


Byron Ellis wrote:
> Is there any particular reason Imports and different from  
> Dependencies? I may be missing something, but importing would seem to  
> imply a dependence relationship which doesn't appear to be honored.  
> rflowcyt (not to pick on it, it just happened to be the package I  
> tried to load) for example imports but does not depend on prada.
> ---
> Byron Ellis (ellis at stat.harvard.edu)
> "Oook" -- The Librarian
> _______________________________________________
> Bioc-devel at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/bioc-devel

Dr. Oleg Sklyar
European Bioinformatics Institute
Wellcome Trust Genome Campus
Cambridge CB10 1SD

Tel   +44-1223-494466
Fax   +44-1223-494468
email osklyar at ebi.ac.uk

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