R help - Mar 2007 - Substituting functions in package - Lattice

Hi,
	I'm trying to learn how a package works but substituting a  
parituclart function with my own (basically the original one with  
some debug statements).
	The package is lattice and the method is "print.trellis" which is a  
S3 method and is not visible.
	To replace this, i sourced a file with the rewritten print.trellis,  
and the old one was replaced.
	However, i get this error when I attempt to print a trellis object  
(e.g an xyplot)
	
	Error in assign("last.object", x, env = .LatticeEnv) :
	object ".LatticeEnv" not found
	
	I notice that .LatticeEnv is defined in zzz.R (in the R folder of  
the lattice source).

	My question, how does one do development on the lattice package  
without having to recompile everything and install a package?

	I read something about emacs and development (i use emacs) in the  
zzz.R file
	"## .First.lib will be used if the NAMESPACE file is missing.  This is
## useful during development, thanks to C-c C-l in Emacs/ESS. It won't
## be used if a NAMESPACE file is present.  Note: Due to registration
## of C functions done in the NAMESPACE file, wireframe (and possibly
## cloud) won't work in this scenario."

	But couldn't quite figure it out.
	Thanks for any help provided.
	Saptarshi


Saptarshi Guha | sapsi@pobox.com | http://www.stat.purdue.edu/~sguha


	[[alternative HTML version deleted]]

You need to set the environment on your version of print.trellis to
match that of the original (at least that is what has worked for me when
trying to do modified functions from the trellis package).  Try
something like:
> environment(print.trellis) <- environment(lattice::print.trellis)
Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Saptarshi Guha
> Sent: Tuesday, March 06, 2007 2:55 PM
> To: R-Help
> Subject: [R] Substituting functions in package - Lattice
> 
> Hi,
> 	I'm trying to learn how a package works but 
> substituting a parituclart function with my own (basically 
> the original one with some debug statements).
> 	The package is lattice and the method is 
> "print.trellis" which is a
> S3 method and is not visible.
> 	To replace this, i sourced a file with the rewritten 
> print.trellis, and the old one was replaced.
> 	However, i get this error when I attempt to print a 
> trellis object (e.g an xyplot)
> 	
> 	Error in assign("last.object", x, env = .LatticeEnv) :
> 	object ".LatticeEnv" not found
> 	
> 	I notice that .LatticeEnv is defined in zzz.R (in the R 
> folder of the lattice source).
> 
> 	My question, how does one do development on the lattice 
> package without having to recompile everything and install a package?
> 
> 	I read something about emacs and development (i use 
> emacs) in the zzz.R file
> 	"## .First.lib will be used if the NAMESPACE file is 
> missing.  This is ## useful during development, thanks to C-c 
> C-l in Emacs/ESS. It won't ## be used if a NAMESPACE file is 
> present.  Note: Due to registration ## of C functions done in 
> the NAMESPACE file, wireframe (and possibly ## cloud) won't 
> work in this scenario."
> 
> 	But couldn't quite figure it out.
> 	Thanks for any help provided.
> 	Saptarshi
> 
> 
> Saptarshi Guha | sapsi at pobox.com | http://www.stat.purdue.edu/~sguha
> 
> 
> 	[[alternative HTML version deleted]]
> 
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