[Python-Dev] bpo-34595: How to format a type name? (original) (raw)

Victor Stinner vstinner at redhat.com
Wed Sep 12 20:33:23 EDT 2018


Hi,

For the type name, sometimes, we only get a type (not an instance), and we want to format its FQN. IMHO we need to provide ways to format the FQN of a type for types and for instances. Here is my proposal:

Python: "!t" for instance

raise TypeError(f"must be str, not {obj!t}")

/* C: "%t" for instance */ PyErr_Format(PyExc_TypeError, "must be str, not %t", obj);

/* C: "%T" for type */ PyErr_Format(PyExc_TypeError, "must be str, not %T", mytype);

Python: ":T" for type

raise TypeError(f"must be str, not {mytype!T}")

Open question: Should we also add "%t" and "%T" formatters to the str % args operator at the Python level?

I have a proof-of-concept implementation: https://github.com/python/cpython/pull/9251

Victor

Victor



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