c - 其中错误消息 ArgumentError : no id given comes from when calling method_missing

Question

当您使用第一个参数作为 'string' 而不是 :symbol 调用 method_missing 时，您会收到以下神秘的错误消息:

BasicObject.send(:method_missing, 'any-method')
ArgumentError: no id given
from (pry):3:in `method_missing'

当您查看source code时对于method_missing

static VALUE
rb_method_missing(int argc, const VALUE *argv, VALUE obj)
{
    rb_thread_t *th = GET_THREAD();
    raise_method_missing(th, argc, argv, obj, th->method_missing_reason);
    UNREACHABLE;
}

没有任何错误消息ArgumentError:没有给出id。它从哪里来？

Answer 1

raise_method_missing()确实引发了该参数错误:

static void
raise_method_missing(rb_thread_t *th, int argc, const VALUE *argv, VALUE obj,
                     int last_call_status)
{
    // ...
    if (argc == 0 || !SYMBOL_P(argv[0])) {
        rb_raise(rb_eArgError, "no id given");
    }
    // ...
}