[Rd] SaveImage, LazyLoad, S4 and all that {was "install.R ... files"}

Martin Maechler maechler at stat.math.ethz.ch
Fri Feb 3 10:41:25 CET 2006

>>>>> "Seth" == Seth Falcon <sfalcon at fhcrc.org>
>>>>>     on Thu, 02 Feb 2006 11:32:42 -0800 writes:

    Seth> Thanks for the explaination of LazyLoad, that's very helpful.
    Seth> On  1 Feb 2006, ripley at stats.ox.ac.uk wrote:
    >> There is no intention to withdraw SaveImage: yes.  Rather, if
    >> lazy-loading is not doing a complete job, we could see if it could
    >> be improved.

    Seth> It seems to me that LazyLoad does something different with respect to
    Seth> packages listed in Depends and/or how it interacts with namespaces.

    Seth> I'm testing using the Bioconductor package graph and find that if I
    Seth> change SaveImage to LazyLoad I get the following:


I had also the vague feeling that  saveImage  was said to be
important when using  S4 classes and methods; particularly when
some methods are for generics from a different package/Namespace
and other methods for `base' classes (or other classes defined
This is the case of 'Matrix', my primary experience here.
OTOH, we now only use 'LazyLoad: yes' , not (any more?)
'SaveImage: yes' -- and honestly I don't know / remember why.


    Seth> ** preparing package for lazy loading
    Seth> Error in makeClassRepresentation(Class, properties, superClasses, prototype,  : 
    Seth> couldn't find function "getuuid"              

    Seth> Looking at the NAMESPACE for the graph package, it looks like it is
    Seth> missing some imports.  I added lines:
    Seth> import(Ruuid)
    Seth> exportClasses(Ruuid)

    Seth> Aside: am I correct in my reading of the extension manual that if one
    Seth> uses S4 classes from another package with a namespace, one
    Seth> must import the classes and *also* export them?

    Seth> Now I see this:

    Seth> ** preparing package for lazy loading
    Seth> Error in getClass("Ruuid") : "Ruuid" is not a defined class
    Seth> Error: unable to load R code in package 'graph'
    Seth> Execution halted   

    Seth> But Ruuid _is_ defined and exported in the Ruuid package.

    Seth> Is there a known difference in how dependencies and imports are
    Seth> handled with LazyLoad as opposed to SaveImage?  

    Seth> Thanks,

    Seth> + seth

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