[Rd] Byte compilation of packages on CRAN

Prof Brian Ripley ripley at stats.ox.ac.uk
Thu Apr 12 07:21:51 CEST 2012

On 11/04/2012 20:36, Matthew Dowle wrote:
> In DESCRIPTION if I set LazyLoad to 'yes' will data.table (for example)
> then be byte compiled for users who install the binary package from CRAN
> on Windows?

No.  LazyLoad is distinct from byte compilation.  All installed packages 
use lazy loading these days (for simplicity: a very few do not benefit 
from it as they use all their objects at startup).

> This question is based on reading section 1.2 of this document :
> http://www.divms.uiowa.edu/~luke/R/compiler/compiler.pdf
> I've searched r-devel and Stack Overflow history and have found
> questions and answers relating to R CMD INSTALL and install.packages()
> from source, but no answer (as yet) about why binary packages for
> Windows appear not to be byte compiled.
> If so, is there any reason why all packages should not set LazyLoad to
> 'yes'. And if not, could LazyLoad be 'yes' by default?

I wonder why you are not reading R's own documentation.  'Writing R 
Extensions' says

'The `LazyData' logical field controls whether the R datasets use 
lazy-loading. A `LazyLoad' field was used in versions prior to 2.14.0, 
but now is ignored.

The `ByteCompile' logical field controls if the package code is 
byte-compiled on installation: the default is currently not to, so this 
may be useful for a package known to benefit particularly from 
byte-compilation (which can take quite a long time and increases the 
installed size of the package).'

Note that the majority of CRAN packages benefit very little from 
byte-compilation because almost all the time of their computations is 
spent in compiled code.  And the increased size also may matter when the 
code is loaded into R.

> Thanks,
> Matthew
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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