On 29 September 2013 at 14:06, Simon Zehnder wrote:
| Dear Rcpp::Users and Rcpp::Devels,
|
| I would like to understand a certain behaviour of my code I encountered
lately.
|
| I am working with CharacterVector and the following behaviour occurred:
|
| void test1 (Rcpp::CharacterVector &charv)
| {
| Rprintf("test1: %s\n", (char*) charv(0));
| }
|
| void test2 (const Rcpp::CharacterVector &str)
| {
| Rprintf("test2: %s\n", (char*) charv(0));
| }
|
| Using a string like "2013-05-04 20:23:21" for the Rcpp::CharacterVector gives
the following outputs:
|
| test1: 2013-05-04 20:23:21
|
| test2: `
|
| This does also not change if I use a cast to const char* in test2. I tried
something similar with strings and printing the c_str() of them, there the
'const' keyword does not make a difference - it always prints the correct
string.
|
| Is this something specific to the Rcpp::CharacterVector, that uses a
string_proxy for its elements returned by the operator ()? Is there a way to
use const Rcpp::CharacterVector and get the behaviour of test1?
Looks like a bug. (But note that const correctness of types build around SEXP
is at best a promise -- we cannot undo the fact the the SEXP _is_ a pointer.)
But hold on for a day til Rcpp 0.10.5 reaches your mirror, or grab it from
CRAN in Vienna. It brings a lot of excellent changes, among them some fine
work by Romain dealing with exactly that. Full announcement coming later once
I am back from running and kid's soccer game.
Dirk
--
Dirk Eddelbuettel | [email protected] | http://dirk.eddelbuettel.com
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