[ESS] Developing R packages under ESS

[Boylan, Ross]

Can anyone suggest to me a good way to develop R packages with ESS?  "good" here means that I  can debug the code and make changes to the code without rebuilding the whole package.

So far I've tried a bunch of different approaches, but none has quite worked.

1. When I had an old (or even new) version of the package in the standard load paths I tended to get "namespace is locked" errors when I modified the code and attempted to read it in.  So I deleted the installation in the standard path.

2. Wrote a script that sourced all the .R files.  But when I change them and reload in ESS I get the error "unable to load <mylibrary>", even if I do C-c C-t C-s to turn off the namespace.  I suspected the problem might have been from evaluating vignette code in an .rnw file, but even if I copied and pasted it into the the main *R* buffer I still get the problem:
 Loading required package: LazarSim
 Error in .requirePackage(package) (from SimParameters.R#35) :                                                                                                                                
   unable to find required package ‘LazarSim’
 In addition: Warning message:
 In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
   there is no package called ‘LazarSim’
BTW, that error happened after I attempted to execute some code from the package, not when I issued any load/library/require type command.

R is running in the directory above the package directory.
Grep confirms my recollection that I don't have code that does require().
Maybe R overrides the basic code for sourcing files?  My test file uses source() to load the source files, which are in the package directory.

Thanks for any help.
Ross