How to raise errors/exceptions by default in mruby? - mruby

Question

I'm getting started with mruby and found out the hard way that an error was occurring in my code, but there was no error reporting. Maybe I am doing something wrong. How can I get errors to appear when they occur?
Excerpt from C code:
mrb = mrb_open();
FILE *f = fopen("example.rb", "r");
mrb_load_file(mrb, f);
fclose(f);
// more C code...
Ruby code which fails without reporting:
# example.rb
def my_method
call_undefined_method
end
my_method()
Ruby code which rescues from the error to display that there was an error:
# example.rb
def my_method
call_undefined_method
rescue => e
puts "Error: #{e.message}"
end
my_method()

Answer 1

You can get exception via mrb->exc
#include <mruby.h>
#include <mruby/variable.h>
#include <mruby/string.h>
#include <stdio.h>
int
main(int argc, char* argv[]) {
mrb_state* mrb = mrb_open();
FILE *f = fopen("example.rb", "r");
mrb_value obj = mrb_load_file(mrb, f);
fclose(f);
if (mrb->exc) {
// Error
obj = mrb_funcall(mrb, mrb_obj_value(mrb->exc), "inspect", 0);
fwrite(RSTRING_PTR(obj), RSTRING_LEN(obj), 1, stdout);
putc('\n', stdout);
} else {
obj = mrb_funcall(mrb, obj, "inspect", 0);
fwrite(RSTRING_PTR(obj), RSTRING_LEN(obj), 1, stdout);
putc('\n', stdout);
}
mrb_close(mrb);
return 0;
}