From edd at debian.org  Mon Feb  4 03:22:30 2008
From: edd at debian.org (Dirk Eddelbuettel)
Date: Sun, 3 Feb 2008 20:22:30 -0600
Subject: [Rd] gdb
In-Reply-To: <878x21cwuw.fsf@DEBLAP1.BeNet>
References: <871w7ualss.fsf@DEBLAP1.BeNet>
	<18341.58878.423585.780727@ron.nulle.part>
	<878x21cwuw.fsf@DEBLAP1.BeNet>
Message-ID: <18342.30438.828619.519320@ron.nulle.part>


On 4 February 2008 at 01:51, Joe Bloggs wrote:
| Dirk Eddelbuettel <edd at debian.org> writes:
| 
| > On 3 February 2008 at 01:08, Joe Bloggs wrote:
| > | I am using gdb to debug a c++ library I made for R using Rcpp.
| > | However, when I step through the code it seems to go all over the place, and some of the variables have been optimized out so I can't see their values.
| > | How can I compile without optimization?
| >
| > Set MAKEFLAGS accordingly, possibly by editing R's Makeconf.  This is
| > documented in the 'R Extensions' manual.
| >
| 
| Thanks, for the benefit of others..
| 
| I changed the CXXFLAGS line in /etc/R/Makeconf from:
| 
| CXXFLAGS = -g -O2
| 
| to:
| 
| CXXFLAGS = -ggdb -O2

Hm, I never seem to have needed -ggdb, for me -g was usually suffcient. Any
idea why you needed -ggdb ?
 
| which seems to work. Changing -O2 to just -O would remove compiler optimizations, but it turns out this wasn't necessary.
| Alternatively I could compile my package with
| 
| MAKEFLAGS="CXXFLAGS=-ggdb -O2" R CMD INSTALL ...
| 
| to temporarily change the flags.
| 
| 
| > | Also, is there any neat way to run R with gdb through emacs?
| >
| > Yes, using 'M-x gdb' to launcg the gdb frontend. I also use ddd on Linux.
| >
| > Using the debugger is also described in the 'R Extensions' manual.
| >
| 
| In the manual it says to run R through gdb by: R -d gdb
| how can I do this in emacs?
| Alternatively how do I run R through gdb after alreay starting gdb?

I thought that was in the manual, but it seems it isn't.  Doug Bates
describes it once or twice a few years back; one quick Google search leads to

	http://tolstoy.newcastle.edu.au/R/help/03a/0566.html

Hope this helps, Dirk

| 
| > Hope this helps, Dirk
| >
| > -- 
| > Three out of two people have difficulties with fractions.
| >
| > ______________________________________________
| > R-devel at r-project.org mailing list
| > https://stat.ethz.ch/mailman/listinfo/r-devel
| 
| ______________________________________________
| R-devel at r-project.org mailing list
| https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Three out of two people have difficulties with fractions.



[Rd] gdb
Dirk Eddelbuettel