[Python] Improve consistency of explicit C++ types in PyArrow files

[asfimport]

Cython files (.pyx) in PyArrow make inconsistent use of explicit C++ typing. Some methods/functions use explicit types for their parameters and others do not.

Also, definition files (.pxd) are not consistent in the use of the reference operator (&) and may not be up-to-date w.r.t. to C++ API.

Reporter: Eduardo Ponce / @edponce
Assignee: Eduardo Ponce / @edponce

Related issues:

• [Python] Missing default values of kernel options in PyArrow (is related to)

PRs and other links:

• GitHub Pull Request #11147

_{Note: This issue was originally created as ARROW-13327. Please see the migration documentation for further details.}

[asfimport]

Eduardo Ponce / @edponce:
Actually, the description files (.pxd) contain the explicit types of the function options' parameters (e.g., SliceOptions in libarrow.pxd), so I do not think it is necessary to add explicit types to the implementation files (.pyx) as currently done for some cases (e.g., SliceOptions in _compute.pyx).

[asfimport]

Eduardo Ponce / @edponce:
It seems that Cython considers pass-by-reference as default for object types. For example, shared_ptr[T] as shared_ptr[T]&. The ampersand seems to not be required. Nevertheless, it does supports and parses the ampersand so it is best to be consistent with C++ parameter types.

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 11147
#11147