Context for shared library

[AB]

How can a shared library written in c get the context from the scheme page that loaded it?

[Lukas Böger]

> How can a shared library written in c get the context from the scheme page that loaded it?

The shared library must define a function (with external linkage) named sexp_init_library. The exact signature can be found in the docs, but its first argument is the context of type sexp.

Hope this helps.

Lukas

[AB]

That helps thanks. 

earlier I copied the ctx and env from sexp_init_library to global variables.

I had it running but would get segmentation faults or the program would just close.

right now I am trying to use a variable with sexp_env_define, it finishes with no errors,

but the next commands gives undefined variable exception.

[Alex Shinn]

Usually you want to use the FFI which will generate this for you.

ast.c is an example shared library written by hand without the FFI.

If you want to copy Scheme variables to globals in C, you should use

sexp_preserve_object to be sure they don't get gc'ed. But in general

this is advanced usage and should be done with caution - sexp_env_define

is safer.

--

Alex

[AB]

I got it working except I get an occasional segmentation fault right at startup. I used

FFI and tried to use sexp_env_define, but the c functions didn't see it.

https://pastebin.com/AEqPSKiS