This is nice! It does introduce an issue though, __doc__ now contains that text signature in its contents, you'll need to tweak doc to ignore the signature at the start (similar to CPythons _PyType_DocWithoutSignature).

Originally posted by @DimitrisJim in #2904 (comment)

Overview

Documentations of methods, types in CPython can have format like below:

<SIGNATURE>
--

<DOCUMENT>

And CPython's __doc__ property strips the signature through _PyType_DocWithoutSignature. Then, when you call <?>.__doc__, you will see only <DOCUMENT>. But RustPython hasn't implemented it so it should be implemented.

Example

Let's see the case of object type.

The full doc is:

PyDoc_STRVAR(object_doc,
"object()\n--\n\n"
"The base class of the class hierarchy.\n\n"
"When called, it accepts no arguments and returns a new featureless\n"
"instance that has no instance attributes and cannot be given any.\n");

As human-familiar:

object()
--

The base class of the class hierarchy.

When called, it accepts no arguments and returns a new featureless
Instance that has no instance attributes and cannot be given any.

And when call print(object.__doc__) in CPython 3.8.0, you will see:

The base class of the class hierarchy.

When called, it accepts no arguments and returns a new featureless
instance that has no instance attributes and cannot be given any.

References

• _PyType_DocWithoutSignature implementation: https://github.com/python/cpython/blob/fa919fdf2583bdfead1df00e842f24f30b2a34bf/Objects/typeobject.c#L158-L169