The methods "get_something()" should be "something()"

[1ucian0]

@jaygambetta expressed discontent with methods of the shape get_something(). It seems he is not the only one.

A quick grep returned:

• qiskit/tools/visualization/_matplotlib.py: get_index(self) See The methods "get_something()" should be "something()" #1346 (comment)
• qiskit/result/_result.py:
  • get_status(self)
  • get_circuit_status(self, icircuit)
  • get_job_id(self)
  • get_ran_qasm(self, name)
  • get_data(self, circuit=None)
  • get_counts(self, circuit=None)
  • get_statevector(self, circuit=None)
  • get_unitary(self, circuit=None)
  • get_snapshots(self, circuit=None)
  • get_snapshot(self, slot=None, circuit=None)
  • get_names(self)
  • get_qubitpol_vs_xval(self, nqubits, xvals_dict=None)
• qiskit/backends/ibmq/api/ibmqconnector.py: The methods "get_something()" should be "something()" #1346 (comment)
  • get_job_url(config, hub=None, group=None, project=None)
  • get_backend_stats_url(config, backend_type, hub=None)
  • get_backend_properties_url(config, backend_type, hub=None)
  • get_backend_url(config, hub, group, project)
  • def get_token(self)
  • get_user_id(self)
  • get_config(self)
  • get_job(self, id_job, hub=None, group=None, project=None,..)
  • get_jobs(self, limit=10, skip=0, backend=None, only_completed=False,...)
  • get_status_job(self, id_job, hub=None, group=None, project=None,...)
  • get_status_jobs(self, limit=10, skip=0, backend=None, filter=None,...)
• qiskit/backends/baseprovider.py: get_backend(self, name=None, **kwargs)
• qiskit/backends/aer/aerprovider.py: get_backend(self, name=None, **kwargs) The methods "get_something()" should be "something()" #1346 (comment)
• qiskit/unrollers/_unrollerbackend.py: get_output(self) The methods "get_something()" should be "something()" #1346 (comment)
• qiskit/unrollers/_dagbackend.py: get_output(self) The methods "get_something()" should be "something()" #1346 (comment)
• qiskit/unrollers/_jsonbackend.py: get_output(self) The methods "get_something()" should be "something()" #1346 (comment)
• qiskit/mapper/_coupling.py:
  • get_qubits(self)
  • get_edges(self)
• qiskit/mapper/_layout.py:
  • get_bits(self)
  • get_wires(self)
• qiskit/dagcircuit/_dagcircuit.py`:
  • get_qubits(self)
  • get_op_nodes(self, op=None)
  • get_named_nodes(self, name)
  • get_cnot_nodes(self)
• qiskit/qasm/_qasm.py:
  • get_filename(self)
  • get_tokens(self)
• qiskit/qasm/_qasmparser.py: get_tokens(self)

In many situations the prefiex get_ simply can be removed. In others, it can be replaced by more specific, like generate_output. If there is a set_something, in that case I think get_something makes sense.

Since this change affects a lot of things, do it in several PRs please.

[jaygambetta]

Yes there are many that we need to fix. The get_backend I think we keep as we have a backends command.

[mtreinish]

The matplotlib one I wouldn't worry about it, it's an internal method on a class only used inside that module (to set anchors in the figure). It's never going to be called anywhere else

[diego-plan9]

For the Results, there is an attempt of discussion at #830. For the rest of instances and potential implementers, please note as well that even if the technical challenge is indeed relatively straightforward (as in, renaming the method and revising the rest of the codebase and test for usages of the method), some discussion might be needed:

• if the change implies a public API change, a deprecation warning should be emitted.
• not all get_xxx functions fall into the same category - there are some that are indeed akin to property setters (ie. where the recommendation linked above very likely applies), but there are others with a different semantic meaning (Jay's example of .get_backend() is one where that distinction is arguably quite strong - it is not getting a property, it involves actually retrieving a backend).

It would probably be a good idea indeed to go case-by-case basis (per class or similar) - other than those nits, it sounds good! Thanks @1ucian0 for starting the effort 👍

[1ucian0]

Maybe select_backend?

[jaygambetta]

lol I really like select_backend but the spec is out and we have so many people using get_backend. But select is so much more descriptive. @diego-plan9 @ajavadia thoughts?

[1ucian0]

Not part of terra any more:

• qiskit/backends/ibmq/api/ibmqconnector.py
• qiskit/unrollers/
• qiskit/backends/aer/aerprovider.py