Le 29/08/13 18:59, Steve Jaffe a écrit :
On 24 Aug 2013 at 09:04, [email protected] wrote:
On 23 August 2013 at 19:33, Subodh Acharya wrote:
But whenever I call sample() in more than 1 file, I get the error
during package compilation.
This is now fixed in svn.
The file did not have include guards and it was defining functions that
were too long to be inlined.
Since I don't want the user to have to link against an RcppArmadillo
library (like we do in Rcpp), I made these functions (SampleReplace, etc
...) templates.
This should allow people to include this file more than once.
The alternative would be to only have declarations of the
SampleReplace, etc ... functions in sample.h and definitions in a .cpp
file in RcppArmadillo, but then we would need users to mess with their
PKG_LIBS, and we would need to store a library we can link against. This
is already a lot of trouble to do this with Rcpp, so I'm not doing that
for RcppArmadillo.
The other alternative is to not host sample in RcppArmadillo but in
another package. I don't have strong opinion on this, but sample is
somewhat of an outlier in RcppArmadillo. RcppArmadillo is just supposed
to make armadillo available. sample is an example use case.
Romain
Another alternative is simply to declare such a function as "inline."
I don't think that works and I've had examples to verify this belief.
Quite recently, implementations of wrap and as for sparse matrices
classes in RcppArmadillo were huge and yet declared as inline. And we
still had the multiple definitions problem. There were other issues with
them, but that's beyond the scope of this thread and this has been fixed
anyway.
This does not mean that it will be physically inlined -- it may or may not
be, at the discretion of the compiler; it only means that the compiler/linker
are responsible for eliminating multiple definitions, ie it simply makes it
legal for the function to be defined in multiple compilation units, "as if" it
were inline.
Include guards won't prevent multiple definition errors when the same header
is included by multiple compilation units.
Sure. This was not the problem, but it was a bit scary to see a header
file without include guards.
Any function defined in a header file,
which is not in a class definition, and is not a template, should be
declared as inline.
If this were true we just would have to declare everything as inline.
I don't mean to create a debate here, but I don't think just using the
inline keyword would have fixed this issue.
Romain
Steve Jaffe
[email protected]
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