method

throw

v1_8_7_72 - Show latest stable - 1 note - Class: Kernel

throw(...) public

Transfers control to the end of the active catch block waiting for symbol. Raises NameError if there is no catch block for the symbol. The optional second parameter supplies a return value for the catch block, which otherwise defaults to nil. For examples, see Kernel::catch.

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/*
 *  call-seq:
 *     throw(symbol [, obj])
 *  
 *  Transfers control to the end of the active +catch+ block
 *  waiting for _symbol_. Raises +NameError+ if there
 *  is no +catch+ block for the symbol. The optional second
 *  parameter supplies a return value for the +catch+ block,
 *  which otherwise defaults to +nil+. For examples, see
 *  <code>Kernel::catch</code>.
 */

static VALUE
rb_f_throw(argc, argv)
    int argc;
    VALUE *argv;
{
    VALUE tag, value;
    struct tag *tt = prot_tag;

    rb_scan_args(argc, argv, "11", &tag, &value);
    tag = ID2SYM(rb_to_id(tag));

    while (tt) {
        if (tt->tag == tag) {
            tt->dst = tag;
            tt->retval = value;
            break;
        }
        if (tt->tag == PROT_THREAD) {
            rb_raise(rb_eThreadError, "uncaught throw `%s' in thread 0x%lx",
                     rb_id2name(SYM2ID(tag)),
                     curr_thread);
        }
        tt = tt->prev;
    }
    if (!tt) {
        rb_name_error(SYM2ID(tag), "uncaught throw `%s'", rb_id2name(SYM2ID(tag)));
    }
    rb_trap_restore_mask();
    JUMP_TAG(TAG_THROW);
#ifndef __GNUC__
    return Qnil;                /* not reached */
#endif
}

April 21, 2009

3 thanks

To throw an exception, use Kernel#raise

Other languages use the term throw for raising exceptions, but Ruby has a specific raise call for that.

throw

Related methods

To throw an exception, use Kernel#raise