Crate extendr_engine

Embeds a a single R process

Using R’s C-API requires the embedding of the R runtime. Thus, when using bindings in libR-sys, it is necessary that either the a R process is the caller, or that the process instantiates an accompanying R process. Otherwise, a run-time error occurs e.g. (signal: 11, SIGSEGV: invalid memory reference) or

Caused by:
process didn't exit successfully: `/extendr/tests/extendrtest/target/debug/deps/extendrtest-59155c3c146ae614` (signal: 11, SIGSEGV: invalid memory reference)

Testing

Within tests, one must use test! or with_r as a wrapper around code that uses the R runtime, e.g.

#[test]
fn testing_r_code() {
    with_r(|| {
     
    });
}

Similarly with test! that is available in extendr_api, one may

#[test]
fn testing_r_code() {
    test! {
     
    };
}

The advantage of test! is that it allows the use of ? in test code, while with_r is not macro-based, thus code formatter rustfmt and rust LSPs (Rust Analyzer, Rust Rover, etc.) works within with_r without any problems.

Binaries

In a binary program, one may use start_r directly in the main-function.

There is no end_r, as we terminate the R process setup, when the parent process terminates.

Functions

start_r

with_r

Ensures that an embedded R instance is present when evaluating f.