Class Exception
In: error.c
Parent: Object

Descendents of class Exception are used to communicate between raise methods and rescue statements in begin/end blocks. Exception objects carry information about the exception—its type (the exception‘s class name), an optional descriptive string, and optional traceback information. Programs may subclass Exception to add additional information.

Methods

backtrace   exception   exception   inspect   message   new   set_backtrace   to_s   to_str  

Public Class methods

exc.exception(string) → an_exception or exc

With no argument, or if the argument is the same as the receiver, return the receiver. Otherwise, create a new exception object of the same class as the receiver, but with a message equal to string.to_str.

Construct a new Exception object, optionally passing in a message.

[Source]

/*
 * call-seq:
 *    Exception.new(msg = nil)   =>  exception
 *
 *  Construct a new Exception object, optionally passing in 
 *  a message.
 */

static VALUE
exc_initialize(argc, argv, exc)
    int argc;
    VALUE *argv;
    VALUE exc;
{
    VALUE arg;

    rb_scan_args(argc, argv, "01", &arg);
    rb_iv_set(exc, "mesg", arg);
    rb_iv_set(exc, "bt", Qnil);

    return exc;
}

Public Instance methods

Returns any backtrace associated with the exception. The backtrace is an array of strings, each containing either ``filename:lineNo: in `method’’’ or ``filename:lineNo.’‘

   def a
     raise "boom"
   end

   def b
     a()
   end

   begin
     b()
   rescue => detail
     print detail.backtrace.join("\n")
   end

produces:

   prog.rb:2:in `a'
   prog.rb:6:in `b'
   prog.rb:10

[Source]

/*
 *  call-seq:
 *     exception.backtrace    => array
 *  
 *  Returns any backtrace associated with the exception. The backtrace
 *  is an array of strings, each containing either ``filename:lineNo: in
 *  `method''' or ``filename:lineNo.''
 *     
 *     def a
 *       raise "boom"
 *     end
 *     
 *     def b
 *       a()
 *     end
 *     
 *     begin
 *       b()
 *     rescue => detail
 *       print detail.backtrace.join("\n")
 *     end
 *     
 *  <em>produces:</em>
 *     
 *     prog.rb:2:in `a'
 *     prog.rb:6:in `b'
 *     prog.rb:10
*/

static VALUE
exc_backtrace(exc)
    VALUE exc;
{
    static ID bt;

    if (!bt) bt = rb_intern("bt");
    return rb_attr_get(exc, bt);
}

With no argument, or if the argument is the same as the receiver, return the receiver. Otherwise, create a new exception object of the same class as the receiver, but with a message equal to string.to_str.

[Source]

/*
 *  Document-method: exception
 *
 *  call-seq:
 *     exc.exception(string) -> an_exception or exc
 *  
 *  With no argument, or if the argument is the same as the receiver,
 *  return the receiver. Otherwise, create a new
 *  exception object of the same class as the receiver, but with a
 *  message equal to <code>string.to_str</code>.
 *     
 */

static VALUE
exc_exception(argc, argv, self)
    int argc;
    VALUE *argv;
    VALUE self;
{
    VALUE exc;

    if (argc == 0) return self;
    if (argc == 1 && self == argv[0]) return self;
    exc = rb_obj_clone(self);
    exc_initialize(argc, argv, exc);

    return exc;
}

Return this exception‘s class name an message

[Source]

/*
 * call-seq:
 *   exception.inspect   => string
 *
 * Return this exception's class name an message
 */

static VALUE
exc_inspect(exc)
    VALUE exc;
{
    VALUE str, klass;

    klass = CLASS_OF(exc);
    exc = rb_obj_as_string(exc);
    if (RSTRING(exc)->len == 0) {
        return rb_str_dup(rb_class_name(klass));
    }

    str = rb_str_buf_new2("#<");
    klass = rb_class_name(klass);
    rb_str_buf_append(str, klass);
    rb_str_buf_cat(str, ": ", 2);
    rb_str_buf_append(str, exc);
    rb_str_buf_cat(str, ">", 1);

    return str;
}

Returns the result of invoking exception.to_s. Normally this returns the exception‘s message or name. By supplying a to_str method, exceptions are agreeing to be used where Strings are expected.

[Source]

/*
 * call-seq:
 *   exception.message   =>  string
 *   exception.to_str    =>  string
 *
 * Returns the result of invoking <code>exception.to_s</code>.
 * Normally this returns the exception's message or name. By
 * supplying a to_str method, exceptions are agreeing to
 * be used where Strings are expected.
 */

static VALUE
exc_to_str(exc)
    VALUE exc;
{
    return rb_funcall(exc, rb_intern("to_s"), 0, 0);
}

Sets the backtrace information associated with exc. The argument must be an array of String objects in the format described in Exception#backtrace.

[Source]

/*
 *  call-seq:
 *     exc.set_backtrace(array)   =>  array
 *  
 *  Sets the backtrace information associated with <i>exc</i>. The
 *  argument must be an array of <code>String</code> objects in the
 *  format described in <code>Exception#backtrace</code>.
 *     
 */

static VALUE
exc_set_backtrace(exc, bt)
    VALUE exc;
    VALUE bt;
{
    return rb_iv_set(exc, "bt", rb_check_backtrace(bt));
}

Returns exception‘s message (or the name of the exception if no message is set).

[Source]

/*
 * call-seq:
 *   exception.to_s   =>  string
 *
 * Returns exception's message (or the name of the exception if
 * no message is set).
 */

static VALUE
exc_to_s(exc)
    VALUE exc;
{
    VALUE mesg = rb_attr_get(exc, rb_intern("mesg"));

    if (NIL_P(mesg)) return rb_class_name(CLASS_OF(exc));
    if (OBJ_TAINTED(exc)) OBJ_TAINT(mesg);
    return mesg;
}

Returns the result of invoking exception.to_s. Normally this returns the exception‘s message or name. By supplying a to_str method, exceptions are agreeing to be used where Strings are expected.

[Source]

/*
 * call-seq:
 *   exception.message   =>  string
 *   exception.to_str    =>  string
 *
 * Returns the result of invoking <code>exception.to_s</code>.
 * Normally this returns the exception's message or name. By
 * supplying a to_str method, exceptions are agreeing to
 * be used where Strings are expected.
 */

static VALUE
exc_to_str(exc)
    VALUE exc;
{
    return rb_funcall(exc, rb_intern("to_s"), 0, 0);
}

[Validate]