Refactor argument handling to enforce positional-only and keyword-only arguments using / and * #834
Description
What should we add?
Description
To improve readability and usability in the Qiskit codebase, we propose refactoring function signatures to clearly define positional-only, positional-or-keyword, and keyword-only arguments using the / and * symbols. Parameters before the slash will be strictly positional, while those after the asterisk will be keyword-only. This approach clarifies the API and aligns with Python standards, as in Scikit-learn.
We can start with function signatures and see which arguments should be made keyword-only or remain positional. Temporary lint disables may be necessary to prevent errors during the transition, as seen in #833.
Example from Pegasos QSVC
def __init__(
self,
quantum_kernel: BaseKernel | None = None,
C: float = 1.0,
num_steps: int = 1000,
precomputed: bool = False,
seed: int | None = None,
) -> None:into
def __init__(
self,
quantum_kernel: BaseKernel | None = None,
*,
C: float = 1.0,
num_steps: int = 1000,
precomputed: bool = False,
seed: int | None = None,
) -> None: