[Rcpp-devel] Need some hep reading files

[Sokol Serguei]

Le 29/07/2022 à 23:43, Roberto Spadim a écrit :
> I don't know if I'm  clear in last message
> What I want to do is something like this, but i don't know if Rcpp can 
> 'convert' the ifstream to SEXP and keep the object intact:
XPtr was designed to wrap any C++ pointer to SEXP structure and make a 
backward conversion too. So I would start with this kind of helper.

For example, see 
https://www.r-bloggers.com/2010/01/external-pointers-with-rcpp/

You have to pay a particular attention to what should happen if on R 
side, your pointer-wrapper goes out of scope and thus becomes a subject 
to garbage collection. Should your ifstream be destroyed automatically 
at this moment or you will do it later by yourself?

Best,
Serguei.


>
> One RCPP function to open the file and return the "ifstream" object
>
> ifstream some_open_function(){
>   ifstream infile;
>   infile.open("afile.dat");
>   return infile;
> }
>
> one read function:
>
> string read_file(ifstream infile){
>   string data;
>   infile >> data;
>   return data;
> }
>
> one close function:
>
> void close_file(ifstream infile){
>    infile.close();
> }
>
>
>
>
>
>
>
>
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