Creating Ruby objects from C

Ruby
1

The following snippet of C code shows my attempt to create a Ruby
string object by invoking the “new” method on the Ruby String class.
I know it would be easier to do this using the rb_str_new or
rb_str_new2 functions. However, I’m trying to understand how to
create arbitrary Ruby objects from C using the “new” method. Can you
spot what’s wrong with this code?

ID class_id = rb_intern(“String”);
VALUE stringClass = rb_const_get(rb_cClass, class_id); // wrong
1st parameter?

ID method_id = rb_intern(“new”);
VALUE s1 = rb_funcall(stringClass, method_id, 1, “test”);
printf(“s1 = %s!\n”, RSTRING(s1)->ptr);

2

On Mar 10, 2007, at 11:11 PM, Mark V. wrote:

ID method_id = rb_intern(“new”);
VALUE s1 = rb_funcall(stringClass, method_id, 1, “test”);
printf(“s1 = %s!\n”, RSTRING(s1)->ptr);

I think I found the answer. Using rb_class_new_instance works and is
much simpler that what I was attempting.

3

On Mar 10, 2007, at 9:11 PM, Mark V. wrote:

The following snippet of C code shows my attempt to create a Ruby
string object by invoking the “new” method on the Ruby String
class. I know it would be easier to do this using the rb_str_new or
rb_str_new2 functions. However, I’m trying to understand how to
create arbitrary Ruby objects from C using the “new” method. Can
you spot what’s wrong with this code?

require ‘rubygems’
require ‘inline’

class X
def initialize
puts “blah”
end
end

class Y
inline do |builder|
builder.c ’
VALUE blah() {
return rb_funcall(rb_path2class(“X”), rb_intern(“new”), 0);
}’
end
end

p Y.new.blah

% ./blah.rb

blah

#<X:0x1090ec4>