From: "Martin J. Dürst" Date: 2012-03-14T17:47:42+09:00 Subject: [ruby-core:43272] Re: [ruby-trunk - Bug #6085] Treatment of Wrong Number of Arguments While we are at it, can we also change the extremely cryptic "for". Whenever I see an error message of the form "wrong number of arguments (X for Y)". Is it X arguments given for Y arguments expected, or X arguments expected for Y arguments given? If I look at the Rubinius example (e.g. "ArgumentError: method 'upcase': given 1, expected 0", I don't have to worry about the directionality, but then I could easily think that I used an argument *value* of 1 where it expected an argument *value* of 0. So the best would be an error message along the following lines: wrong number of arguments (given: X, expected: Y) Regards, Martin. On 2012/03/13 20:38, Yusuke Endoh wrote: > Hello, > >> On Mon, Mar 12, 2012 at 10:31 AM, Yui NARUSE wrote: >>> Use one of follwing: >>> * https://github.com/marcandre/ruby/compare/rb_arity_check >>> * https://github.com/marcandre/ruby/compare/rb_arity_check.diff >>> * https://github.com/marcandre/ruby/compare/rb_arity_check.patch >> >> Nice, thanks! I'll provide this kind of link in the future, quite helpful. > > Cool, thanks. > > > 2012/3/13, Marc-Andre Lafortune: >> On Mon, Mar 12, 2012 at 8:07 AM, Yusuke Endoh wrote: >>> One concern: I'm afraid if this change affects people who parses >>> the message string of WNA. What do you think? There is not such >>> people, is there? I don't want to be pedantic, but I can't feel >>> sure because I can no longer use Google codesearch... Google!! >> >> The error type is part of the language specs, but I feel like error messages >> are not meant to be parsed and are subject to change. In this particular >> case, I just checked and Rubinius gives different error messages >> (ArgumentError: method 'upcase': given 1, expected 0). > > Sounds good. At least, Rubinius community does not know any actual > case where WNA message is parsed. > > >> The changes I propose >> are also minimal in their approach and make parsing even easier! > > You know, making parsing easy is not the purpose or the right way. > My concern is just about compatiblity. > > >>> Anyway, I agree that the current is awkward. If no one complains, >>> I'm positive to import it tentatively. >> >> Thanks. Just let me know after you've looked at it and I'll gladly commit >> these. > > Looks good to me. > It brings not only behavior consistency but also good refactoring > effect. > > I noticed some minor issues below. > > vm_insnhelper.c: > > +static inline VALUE > +rb_arg_error_new(int argc, int min, int max) { > + const char *template = "wrong number of arguments (%d for %d..%d)"; > + if (min == max) { > + template = "wrong number of arguments (%d for %d)"; > + } > + else if (max == UNLIMITED_ARGUMENTS) { > + template = "wrong number of arguments (%d for %d+)"; > + } > + return rb_exc_new3(rb_eArgError, rb_sprintf(template, argc, min, max)); > +} > > It would be good to match the number of %d and actual arguments. > > > eval.c: > > - if (i< argc) goto wrong_args; > + if (i< argc) rb_raise(rb_eArgError, "wrong arguments"); > > I guess this line can be removed, though this is not your fault. > > > test/ruby/test_arity.rb > > assert_equal "0 for 1", err_mess{ "".sub!{} } > > This assertion fails. Did you mean "0 for 1..2" ? > > >>> Off topic. Are you interested in improving a keyword argument? >>> There is some issues on its implementation, but I have no time to >>> work on it :-( >> >> I'm not sure I have the technical skills needed, but I can definitely try to >> help. In any case I wanted to work on checking for named arguments and >> giving a better error message in those cases too. What else could I help on? > > So far, the remaining issues I know are better error message, and #5989. >