[Rcpp-devel] Is the order of initializations within a data type defined?

[Dirk Eddelbuettel]

On 24 March 2010 at 13:31, Douglas Bates wrote:
| I find myself writing code like
| 
|    Rcpp::NumericVector mu(arg);
|    Rcpp::NumericVector eta(mu.size());
| ...
| 
| because I need to ensure that mu is constructed from the argument SEXP
| before its size can be used to construct eta.  Is the order of
| initializations compiler-dependent or defined by the standard?  If
| defined by the standard I could write
| 
|    Rcpp::NumericVector mu(arg), eta(mu.size());
| 
| and expect it to work as intended.  Does anyone know if I can count on
| left-to-right ordering of initializations?

Interesting question, and I can't offer more than a firm 'not sure'. You
could for now put some of our conditional logging in the constructor as some
other classes (that take a string as well and then print that string, say) so
that you could at least test with the compiler you happen to using today.

Strictly personally speaking I quite like

    Rcpp::NumericVector mu(arg);
    Rcpp::NumericVector eta(mu.size());

as it gives me ample space to the right comment.
 
Dirk

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