Creating and raising custom exception in Ruby C extension

Ruby
1

Hi, I’m trying to create a CustomError exception in a Ruby C extension
and raise it:

VALUE class_standard_error = rb_const_get(rb_cObject,
rb_intern(“StandardError”));
VALUE class_custom_error = rb_define_class_under(class_standard_error,
“ClassError”, rb_cObject);
rb_raise(class_custom_error, “Oh, a custom error occurred !!!”);

Unfortunatelly when running it I get:

ArgumentError: wrong number of arguments(1 for 0)
./test_unit.rb:22:in initialize' ./test_unit.rb:22:innew’
./test_unit.rb:22:in my_function' ./test_unit.rb:22:intest_01

Being “my_function” the Ruby method calling to the above C code.

I suspect that the line:
rb_raise(class_custom_error, “Oh, a custom error occurred !!!”);
is not correct. How should look the first argument?

Thanks a lot.

2

El Jueves, 22 de Octubre de 2009, Iñaki Baz C. escribió:

ArgumentError: wrong number of arguments(1 for 0)

Thanks a lot.

By inspecting the API I’ve realized that first argument must be an
instance/object of the class:

– rb_raise(VALUE exception_object, const char* format_string, …)

So I must use “rb_class_new_instance”, am I right?

3

El Jueves, 22 de Octubre de 2009, Iñaki Baz C. escribió:

Hi, I’m trying to create a CustomError exception in a Ruby C extension and
raise it:

VALUE class_standard_error = rb_const_get(rb_cObject,
rb_intern(“StandardError”)); VALUE class_custom_error =
rb_define_class_under(class_standard_error, “ClassError”, rb_cObject);
rb_raise(class_custom_error, “Oh, a custom error occurred !!!”);

Ops, this is wrong as ClassError should be a child of StandardError
rather
than a be under it.

4

El Jueves, 22 de Octubre de 2009, Iñaki Baz C. escribió:

ArgumentError: wrong number of arguments(1 for 0)
./test_unit.rb:22:in initialize' ./test_unit.rb:22:innew’
./test_unit.rb:22:in my_function' ./test_unit.rb:22:intest_01

Being “my_function” the Ruby method calling to the above C code.

I suspect that the line:
rb_raise(class_custom_error, “Oh, a custom error occurred !!!”);
is not correct. How should look the first argument?

Let’s try the following real code:

VALUE class_standard_error = rb_const_get(rb_cObject,
rb_intern(“StandardError”));
VALUE argv[0];
VALUE new_error = rb_class_new_instance(0, argv,
class_standard_error);
rb_raise(new_error, “Oh an error ocurred !!!”);

When calling the function containing it from Ruby I get:

NoMethodError: undefined method `new’ for #<StandardError:
StandardError>

What am I doing wrong?
Thanks a lot.

5

On Thu, Oct 22, 2009 at 3:55 PM, Iñaki Baz C. [email protected]
wrote:

    VALUE class_standard_error = rb_const_get(rb_cObject, rb_intern(“StandardError”));
    VALUE argv[0];
    VALUE new_error = rb_class_new_instance(0, argv, class_standard_error);
    rb_raise(new_error, “Oh an error ocurred !!!”);

why not simple:

VALUE custom_error = rb_define_class(“CustomError”, rb_eStandardError);
rb_raise(custom_error, “An error occured!”);

6

El Jueves, 22 de Octubre de 2009, Iñaki Baz C. escribió:

is not correct. How should look the first argument?
NoMethodError: undefined method `new’ for #<StandardError: StandardError>

What am I doing wrong?

Definitively the line
rb_raise(new_error, “Oh an error ocurred !!!”);
is wrong. I think that “VALUE exception_object” (as the function
requires as
first argument) cannot be a class instance.

API:
rb_raise(VALUE exception_object, const char* format_string, …)

7

El Jueves, 22 de Octubre de 2009, Nikolai L. escribió:

On Thu, Oct 22, 2009 at 3:55 PM, Iñaki Baz C. [email protected] wrote:

   VALUE class_standard_error = rb_const_get(rb_cObject,

rb_intern(“StandardError”)); VALUE argv[0];
VALUE new_error = rb_class_new_instance(0, argv,
class_standard_error); rb_raise(new_error, “Oh an error ocurred !!!”);

why not simple:

VALUE custom_error = rb_define_class(“CustomError”, rb_eStandardError);
rb_raise(custom_error, “An error occured!”);

Thanks, I’ve realized right now that first parameter in “rb_raise” can
be
“VALUE class”.

Let me try :slight_smile:

Really thanks a lot.

8

El Jueves, 22 de Octubre de 2009, Iñaki Baz C. escribió:

rb_raise(custom_error, “An error occured!”);

Thanks, I’ve realized right now that first parameter in “rb_raise” can be
“VALUE class”.

Let me try :slight_smile:

Really thanks a lot.

Done thanks to you:

VALUE class_xdms_error = rb_define_class(“XDMSError”,
rb_eStandardError);
VALUE class_xdms_url_parsing_error =
rb_define_class(“XDMSURLParsingError”,
class_xdms_error);
rb_raise(class_xdms_url_parsing_error, “An error occured!”);

:slight_smile: