inst/developer-notes.md

In callr: Call R from R

Design of the internals

There are a lot of possible ways to implement this package, to minimize duplication. This is the API we want:

r(fun, args, ...)
r_safe(fun, args, ...)

r_bg(fun, args, ...)
r_bg_safe(fun, args, ...)

rcmd(cmd, cmdargs, ...)
rcmd_safe(cmd, cmdargs, ...)

rcmd_bg(cmd, cmdargs, ...)
rcmd_bg_safe(cmd, cmdargs ...)

The _safe versions are easy to deal with, they just call the non-_safe versions with different arguments.

For the other versions, this is what they need to do:

r

1. convert / check arguments
2. save function to a file
3. create script file
4. set up profiles
5. set up library path
6. set up LIB and PROFILE env vars
7. set up callbacks (combine show and callbacks)
8. run the R process
9. write stdout & stderr to file, if needed
10. fail on status, if requested
11. get the result

r_bg

1. convert / check arguments
2. save function to a file
3. create script file
4. set up profiles
5. set up library path
6. set up LIB and PROFILE env vars
7. start the R process in the bg

rcmd

1. convert / check arguments
2. get the R binary and its arguments
3. set specified wd
4. set up profiles
5. set up library path
6. set up callbacks (combine show and callbacks)
7. set up LIB and PROFILE env vars
8. run the R process
9. write stdout & stderr to file, if needed
10. fail on status, if requested

rcmd_bg

1. convert/check arguments
2. get the R binary and its arguments
3. set specified wd
4. set up profiles
5. set up library path
6. set up LIB and PROFILE env vars
7. run the R process in the bg

Building blocks

Always run, check_my_args:

1. convert / check arguments

Run by r and r_bg, setup_script_files:

1. save function to a file
2. create script file

Always run, setup_context:

This is run with . as the working directory for r and r_bg.

1. set specified wd
2. set up profiles
3. set up library path
4. set up LIB and PROFILE env vars

callr documentation built on Nov. 2, 2022, 5:09 p.m.