On 14 December 2013 14:56, Vajrasky Kok <sky....@speaklikeaking.com> wrote: > Greetings, > > When fixing/adding error message for wrong type of argument in C code, > I am always confused, how long the wrong type is the ideal? > > The type of error message that I am talking about: > > "Blabla() argument 1 must be integer not wrong_type". > > We have inconsistency in CPython code, for example: > > Python/sysmodule.c > =============== > PyErr_Format(PyExc_TypeError, > "can't intern %.400s", s->ob_type->tp_name); > > Modules/_json.c > ============ > PyErr_Format(PyExc_TypeError, > "first argument must be a string, not %.80s", > Py_TYPE(pystr)->tp_name); > > > Objects/typeobject.c > =============== > PyErr_Format(PyExc_TypeError, > "can only assign string to %s.__name__, not '%s'", > type->tp_name, Py_TYPE(value)->tp_name); > > So is it %.400s or %.80s or %s? I vote for %s. > > Other thing is which one is more preferable? Py_TYPE(value)->tp_name > or value->ob_type->tp_name? I vote for Py_TYPE(value)->tp_name. > > Or this is just a matter of taste?
The idiom has shifted over time, but the preference more recently is definitely for length limiting user provided identifiers (which are generally type names) to limit the maximum length of error messages (to add another variant to the mix, PEP 7 has "%.100s" in an example about breaking long lines that happens to include reporting TypeError). The question should probably be addressed directly in PEP 7, and I'd be inclined to just bless the "%.400s" variant for future code. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
