static symbols too?

June 5, 2010

(This article was first published on BioStatMatt, and kindly contributed to R-bloggers)

Continuing in the context of this previous post

1. Select a static symbol from the R sources, like Connections

$ grep "static Rconnection Connections" src/main/connections.c
static Rconnection Connections[NCONNECTIONS];

2. Get its address

$ objdump -t `R RHOME`/bin/exec/R | awk '/ Connections/ {print $1}'

3. Use the symbol

> library(inline)
> code <- "
+     typedef struct { char *class, *description; } *Rconnection;
+     Rconnection *Connections = (Rconnection*)0x000000000093b700;
+     return mkString(Connections[0]->description);
+ "
> ConZeroDesc <- cfunction(signature(), code, language="C")
> ConZeroDesc()
[1] "stdin"

This effect could probably be prevented by selecting additional compiler and/or and linker options.

P.S. Nice job Oleg Sklyar, Duncan Murdoch, Mike Smith, Dirk Eddelbuettel, Romain Francois with inline-0.3.5

To leave a comment for the author, please follow the link and comment on their blog: BioStatMatt. offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL, Eclipse, git, hadoop, Web Scraping) statistics (regression, PCA, time series, trading) and more...

If you got this far, why not subscribe for updates from the site? Choose your flavor: e-mail, twitter, RSS, or facebook...

Tags: ,

Comments are closed.


Never miss an update!
Subscribe to R-bloggers to receive
e-mails with the latest R posts.
(You will not see this message again.)

Click here to close (This popup will not appear again)