[Rcpp-devel] Strange behavior with boost::program_options

[Kevin Ushey]

If I had to guess, maybe there is some initialization that occurs when
your mylib::Simulation object is constructed, and you need to ensure
that code is only run once? (Perhaps the code that defines the program
options needs to be hidden behind an initialization flag, or something
like that)

Nonetheless, this isn't really an Rcpp question, and it's hard to know
for sure without seeing how your Simulation object is defined.

On Tue, Jul 5, 2016 at 10:56 PM, Watal M. Iwasaki <heavy.watal at gmail.com> wrote:
> Hi all,
>
> I have been trying to make an R function to call my C++ simulation program
> in this way:
> ```c++
> // [[Rcpp::plugins(cpp14)]]
> #include <Rcpp.h>
> #include <mylib.hpp>
> // [[Rcpp::export]]
> std::string run_simulation(Rcpp::CharacterVector
> args=Rcpp::CharacterVector::create()) {
>     auto vs_args = Rcpp::as<std::vector<std::string>>(args);
>     mylib::Simulation sim(vs_args);
>     sim.run();
>     return sim.results();
> }
> ```
>
> The class `Simulation` parses arguments with `boost::program_options` and is
> implemented in `libmylib.dylib`, which can be linked with `PKG_LIBS =
> -lmylib`. Both `devtools::check()` and independent `Rcpp::sourceCpp()` can
> successfully build the function `run_simulation()`. It runs perfectly as I
> intended **only if it is the first call**. The second time I call
> `run_simulation('-v')`, I get the following error:
> ```
> Error: option '-v' is ambiguous and matches different versions of
> '--verbose'
> ```
>
> Other options like `-h` or `--mutation=0` raise the same error. It indicates
> that every option is re-defined after the first call (maybe?). Calling
> without any argument is always OK, and an executable `a.out` built with
> `main.cpp -lmylib` has no problem. I guess the key is how C++ objects are
> cached in R environments. Is this a bug in Rcpp? Or am I missing something?
>
> Thanks,
>
> --
> Watal M. Iwasaki / 岩嵜 航
> SOKENDAI, Graduate University for Advanced Studies,
> Hayama, Kanagawa 240-0193, Japan
> +81-46-858-1576
> https://heavywatal.github.io/
>
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