Let scalar * tensor fall back to the tensor's reflected operator

[anishmehta24]

Description

scalar * tensor (and +, -, /, **, comparisons, bitwise ops) raised TypeError: Cannot convert b to a scalar type, because the scalar operator methods called the op directly. Python only tries the right operand's reflected method (TensorVariable.__rmul__) when the left one returns NotImplemented.

The binary operator methods on _scalar_py_operators now go through a small helper that returns NotImplemented when either operand can't be converted with as_scalar, the same idea as the try/except in TensorVariable.__add__. Errors raised by the op itself still propagate, so test_mod_complex_fail keeps getting ComplexError.

Added test_scalar_tensor_binary_op, parametrized over the operators, next to test_rtruediv; it fails on main. tests/scalar and tests/tensor/test_elemwise.py pass.

Related Issue

• Closes Scalar * Tensor operations fails #1097
• Related to #

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)
• If you are a pro: each commit corresponds to a relevant logical change

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):