plugin convenience function for getting the entry point object

[1ucian0]

I was playing with staged pass managers when a wild plugin appears!

from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
from qiskit.transpiler.preset_passmanagers.plugin import list_stage_plugins

for s in generate_preset_pass_manager(1).stages:
    print(s, list_stage_plugins(s))

init []
layout []
routing ['basic', 'lookahead', 'none', 'sabre', 'stochastic']
translation ['ibm_dynamic_circuits']
optimization []
scheduling []

I never saw ibm_dynamic_circuits before so I was curious to understand where it was coming from. I can imagine this might happen more and more often as the Qiskit plugin ecosystem grows. So I created entry_point_obj to get extra information about it:

from qiskit.transpiler.preset_passmanagers.plugin import entry_point_obj
entry_point_obj('translation', 'ibm_dynamic_circuits')

<qiskit_ibm_provider.transpiler.plugin.IBMTranslationPlugin at 0xdeadbeef>

In this way, you can not only know from where the plugin is coming, but also check the docstrings and get more help on what it does.

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[coveralls]

Pull Request Test Coverage Report for Build 4490507190

• 8 of 8 (100.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.004%) to 85.39%

---

Files with Coverage Reduction	New Missed Lines	%
qiskit/circuit/tools/pi_check.py	1	91.23%
qiskit/transpiler/passes/synthesis/unitary_synthesis.py	1	94.64%
qiskit/visualization/circuit/text.py	1	94.96%
qiskit/pulse/library/waveform.py	3	91.67%

Totals
Change from base Build 4474816332:	-0.004%
Covered Lines:	68022
Relevant Lines:	79660

---

💛 - Coveralls

[taalexander]

This seems reasonable, would it also make sense to return a dict of all possibilities?

[1ucian0]

You mean something like this?

>>> entry_point_obj_by_stage('routing')
{'basic': <obj>, 'lookahead': <obj>, ...}

[jakelishman]

This seems generally useful to me for easy discoverability for me. I'd perhaps prefer to call the function something that makes it clear that it relates to pass manager stage plugins since "entry point" is just generic Python terminology and Qiskit also has entry points for synthesis plugins.

I'm fine to add the idea that Thomas suggested as well, though left to my own devices I probably wouldn't bother - as far as I understand it, it just boils down to

def passmanager_stage_plugin_map(stage):
    manager = getattr(PassManagerStagePluginManager(), f"{stage}_plugins")
    return {name: manager[name].obj for name in manager.names()}

which I'm not sure is worth the extra function, but I think it's a very subjective answer, so I don't feel strongly.

[1ucian0]

I'd perhaps prefer to call the function something that makes it clear that it relates to pass manager stage plugins since "entry point" is just generic Python terminology and Qiskit also has entry points for synthesis plugins.

I went for passmanager_stage_plugins to make it slightly shorter. But it is basically your code now (adding you as co-author). See b21c622

[jakelishman]

I think the docs failure is just because this line needs updating with the new name.

[1ucian0]

yeap.. forgot that. Fixed in 6135d9f

[jakelishman]

This ? syntax is specific to IPython - you maybe want to use the standard Python built-in help instead.

[1ucian0]

fixed in 6135d9f

[jakelishman]

Symengine 0.10!! 🎉

[jakelishman]

This was proposed well ahead of the 0.24 feature freeze (and the 0.23 feature freeze!) and its test failures were related to other problems in CI at the time. I've just brought it up-to-date (I was already a co-author), and assuming its tests pass immediately, I'm happy to just fold it into the rest of the release.