r - Use a small amount of C++-level code from another package -

there r package defines handy functions extracting files zip archives std::string in c++. i'd use functions in own packages, can't link them because header not in inst/include directory of original package.

my question based on understanding c++-level code isn't available outside package unless header in inst/include.

to use code, options are:

1. ask package maintainer move c++ header file inst/include directory can call package linkingto in description file.

2. copy , acknowledge code, means propagating gpl-3 licence own package.

3. copy , pointlessly alter code evade copyright.

4. copy code, 20 lines, don't alter it, don't acknowledge it, , don't propagate gpl-3 licence.

5. create separate, tiny package makes code want available in inst/include, acknowledges original author, , propogates gpl-3 licence (but not actual package, includes it).

are there other options? have misunderstood writing r extensions or rcpp?

clarification: not @ condone options 3 , 4, are, in view, cheating. hence question. people reading answers see such things regarded cheating. things people consider when doing 'right thing' harder simple imports: package, why included them.

the viable options options 1 , 2.

option 1 works provided r maintainers willing give code under license other gpl. of course implies going link against dual-licensed code, not against of r.

option 2 works if willing use gpl code , code links code.

option 3 definition of plagiarism, , not option.

option 4 fishy, unethical, , bit difficult achieve you've publicly announced option.

option 5 not work since gpl applies separate package well, , extension applies code using package.