[Python-Dev] How long the wrong type of argument should we limit (or not) in the error message (C-api)?

[Vajrasky Kok]

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?

Thank you.

Vajrasky Kok