cimport cython
@cython.embedsignature(True)
cdef class MyClass(object):
def __init__(self, x):
pass
def __call__(self, y):
pass
from sage.misc.sageinspect import sage_getargspec
print(sage_getargspec(MyClass("hello")))
ArgSpec(args=['x'], varargs=None, keywords=None, defaults=None)