[Rd] Lazy loading - importance of NAMESPACE

From: Philippe Grosjean <phgrosjean_at_sciviews.org>
Date: Mon 18 Oct 2004 - 02:33:48 EST


Hello all,

Following a question in r-help, where I was wondering why my large package with lots of "Depends:" did load so slowly (almost 30 sec in lazy loading in R 2.0.0 under Win XP, for 3.4 sec in R 1.9.1 on the same machine), I discovered that a correct namespace changes everything: with the namespace added, loading of my package drops to circa 1 sec, which is more that three times faster than in R 1.9.1 without lazy loading,... and about 30 times faster than without the namespace in R 2.0.0!

First of all, congratulation for implementing lazy loading!

Second, I look in the documentation, and in the Brian Ripley's article in R News 2/2004, and I found nowhere a place where the importance of namespace is stressed for lazy loading (although Brian Ripley explains in several places differences in lazy loading with and without namespace). I think it is something important and, unless I miss it in the documentation, it would be useful to tell somewhere that a namespace is strongly recommended in conjonction with lazy loading...

Finally, a question:
>From R News 2/2004 p. 30: "a 'Imports:' field for packages whose namespaces
are used but do not need to be attached." OK, functions in these namespaces
are available to me, without attaching the package. Now, if I need to attach these packages at a later time because I will use some of their functions from the command line, then, is this package referred twice (once in my package environment, once attached to the search path)? If yes, what is the drawback in term of ressources and speed ('Imports' versus 'Depends', both in loading, and in use of such a package)?

Best,

Philippe Grosjean

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