[Rd] gdb

[Dirk Eddelbuettel]

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