Probable Printer Bug

[czgdp1807]

While I was working on sympy/sympy#17783 I observed that the following code doesn't work on setting, USE_SYMENGINE=true. However, it works perfectly fine without symengine as backend.

from sympy import symbols, S, srepr
from sympy.physics.mechanics import Point, ReferenceFrame, Dyadic, RigidBody
from sympy.physics.mechanics import dynamicsymbols, outer, inertia
from sympy.physics.mechanics import inertia_of_point_mass
from sympy.core.backend import expand

from sympy.utilities.pytest import raises

N = ReferenceFrame('N')
m, Ix, Iy, Iz, a, b = symbols('m, I_x, I_y, I_z, a, b')
Io = inertia(N, Ix, Iy, Iz)
o = Point('o')
p = o.locatenew('p', a * N.x + b * N.y)
R = RigidBody('R', o, N, m, (Io, o))
Ip = R.parallel_axis(p)
Ip_expected = inertia(N, Ix + m * b**2, Iy + m * a**2,
                        Iz + m * (a**2 + b**2), ixy=-m * a * b)

print(Ip)
print(Ip_expected)

With USE_SYMENGINE=true,

Traceback (most recent call last):
  File "sympy_debug.py", line 19, in <module>
    print(Ip)
  File "/home/gagandeep/sympy/sympy/physics/vector/dyadic.py", line 328, in __str__
    arg_str = VectorStrPrinter().doprint(ar[i][0])
  File "/home/gagandeep/sympy/sympy/printing/printer.py", line 249, in doprint
    return self._str(self._print(expr))
  File "/home/gagandeep/sympy/sympy/printing/printer.py", line 287, in _print
    return getattr(self, printmethod)(expr, **kwargs)
  File "/home/gagandeep/sympy/sympy/printing/str.py", line 50, in _print_Add
    terms = self._as_ordered_terms(expr, order=order)
  File "/home/gagandeep/sympy/sympy/printing/printer.py", line 304, in _as_ordered_terms
    return expr.as_ordered_terms(order=order)
AttributeError: 'Add' object has no attribute 'as_ordered_terms'

With USE_SYMENGINE=false,

(I_x + b**2*m)*(N.x|N.x) + (I_y + a**2*m)*(N.y|N.y) + (I_z + m*(a**2 + b**2))*(N.z|N.z) - a*b*m*(N.x|N.y) - a*b*m*(N.y|N.x)
(I_x + b**2*m)*(N.x|N.x) - a*b*m*(N.x|N.y) - a*b*m*(N.y|N.x) + (I_y + a**2*m)*(N.y|N.y) + (I_z + m*(a**2 + b**2))*(N.z|N.z)

[certik]

@czgdp1807 thanks a lot for reporting it! It looks like the Python wrappers have to implement the Add.as_ordered_terms() function to be compatible with SymPy.