A Challenge

[wtd]

Beyond the usual TYS questions, I have a challenge for those who consider themselves good Ruby programmers.

I have the following C function:

code:

#include <stdio.h> void print_foo() {    puts("foo"); }

Make it possible to call this function from Ruby. Do not modify the "print_foo" C function itself, though you may add more code to the "foo.c" source file.

code:

>> require "foo" => true >> print_foo foo => nil >>

[wtd]

A further challenge along the same lines.

Write pure Ruby code which does the same as this Ruby extension written in C.

code:

#include <ruby.h> static VALUE cFoo; static VALUE foo_initialize(VALUE self) {    rb_iv_set(self, "@bar", rb_int_new(42)); } static VALUE foo_set_bar(VALUE self, VALUE new_val) {    int old_bar = FIX2INT(rb_iv_get(self, "@bar"));    int new_bar = FIX2INT(new_val);    if (new_bar > old_bar)    {       rb_iv_set(self, "@bar", new_val);    } } void Init_foo() {    cFoo = rb_define_class("Foo", rb_cObject);    rb_define_method(cFoo, "initialize", foo_initialize, 0);    rb_define_attr(cFoo, "bar", 1, 0);    rb_define_method(cFoo, "bar=", foo_set_bar, 1); }

[rdrake]

The first one I can get to work, but not 100% correctly.

code:

#include <stdio.h> #include <ruby.h> static VALUE foo_class; void print_foo() {    puts("foo"); } static VALUE foo_initialize(VALUE self) {    print_foo(); } void Init_foo() {    foo_class = rb_define_class("Foo", rb_cObject);    rb_define_method(foo_class, "initialize", foo_initialize, 0);    rb_define_attr(foo_class, "bar", 1, 0);    rb_define_method(foo_class, "bar", foo_initialize, 0); }

Here's how you use it

code:

> require 'foo' => true > Foo.new foo

I think that's close enough.

It looks like the second would be something like the following.

code:

class Foo   def initialize     @bar = 42   end     def bar(new_val)     old_bar = @bar     new_bar = new_val         if new_bar > old_bar then       @bar = new_val     end   end end

Use the following code to test it.

code:

foobar = Foo.new foobar.bar(41)

I think that's it anyways.

[wtd]

Close, but not quite.

[rdrake]

How about this for the second?

code:

class Foo   def initialize     @bar = 42   end     def bar=(new_val)     old_bar = @bar     new_bar = new_val         if new_bar > old_bar then       @bar = new_val     end   end end Foo.new.bar=(41)

My solution to the first is posted above.

[wtd]

cartoon_shark wrote:

How about this for the second?

code:

class Foo   def initialize     @bar = 42   end     def bar=(new_val)     old_bar = @bar     new_bar = new_val         if new_bar > old_bar then       @bar = new_val     end   end end Foo.new.bar=(41)

My solution to the first is posted above.

Very good.

Your answer to the first one is too complicated.

code:

#include <stdio.h> #include <ruby.h> void print_foo() {    puts("foo"); } static VALUE wrapped_print_foo(VALUE self) {    print_foo();    return Qnil; } void Init_foo() {    rb_define_method(rb_cObject, "print_foo", wrapped_print_foo, 0); }

[wtd]

http://ruby-doc.org/doxygen/1.8.2/ruby_8h.html

[rdrake]

No wonder why I turned to Ruby...