Ignore fewer flake8 rules, add flake8-bugbear

.flake8

@@ -1,4 +1,13 @@
 [flake8]
+# we choose to use 100 rather than Black's default 88
 max-line-length = 100
-ignore = E203,E999,E741,E126,E127,F401,F403,F405,F811,F841,E743,W503
-exclude = gen3,external
+# E203 : space before ":" (not PEP8 compliant)
+# E741 : ambiguous variable name (unfortunately we need to use "I")
+# E743 : ambiguous function definition (unfortunately we need to use "I")
+# W503 : line break before binary operator (not PEP8 compliant)
+ignore = E203, E741, E743, W503
+# __init__.py            : unused imports for maintaining backwards compatibility / exposing an API
+# external               : vendored external libraries
+# gen3                   : autogenerated parser code
+# operator_estimation.py : unused imports for maintaining backwards compatibility
+exclude = __init__.py, external,  gen3, operator_estimation.py

.gitlab-ci.yml

@@ -15,70 +15,70 @@ services:
     alias: quilc
     command: ["-R"]
 
-test-py36:
+build-docs:
   image: python:3.6
   tags:
     - github
   script:
+    - apt-get update && apt-get install -y pandoc
     - make install
     - make requirements
-    - make test
-  coverage: '/TOTAL.*\s(\d+)%/'
+    - make docs
 
-test-py37:
-  image: python:3.7
+check-format:
+  image: python:3.6
   tags:
     - github
   script:
     - make install
     - make requirements
-    - make test
+    - make check-format
 
-test-py38:
-  image: python:3.8
+check-style:
+  image: python:3.6
   tags:
     - github
   script:
     - make install
     - make requirements
-    - make test
+    - make check-style
 
-style:
+check-types:
   image: python:3.6
   tags:
     - github
   script:
     - make install
     - make requirements
-    - make style
+    - make check-types
 
-typecheck:
+test-py36:
   image: python:3.6
   tags:
     - github
   script:
     - make install
     - make requirements
-    - make typecheck
+    - make test
+  coverage: '/TOTAL.*\s(\d+)%/'
 
-formatcheck:
-  image: python:3.6
+test-py37:
+  image: python:3.7
   tags:
     - github
   script:
     - make install
     - make requirements
-    - make formatcheck
+    - make test
 
-docs:
-  image: python:3.6
+test-py38:
+  image: python:3.8
   tags:
     - github
   script:
-    - apt-get update && apt-get install -y pandoc
     - make install
     - make requirements
-    - make docs
+    - make test
 
 ####################################################################################################
 # MASTER-ONLY JOBS

CHANGELOG.md

@@ -12,6 +12,10 @@ Changelog
 -   Use [Black](https://black.readthedocs.io/en/stable/index.html) for code style
     and enforce it (along with a line length of 100) via the `style` (`flake8`)
     and `formatcheck` (`black --check`) CI jobs (@karalekas, gh-1132).
+-   Ignore fewer `flake8` style rules, add the `flake8-bugbear` plugin, and
+    rename the style-related `Makefile` targets and CI jobs so that they have
+    a uniform naming convention: `check-all`, `check-format`, `check-style`,
+    and `check-types` (@karalekas, gh-1133).
 
 ### Bugfixes
 

CONTRIBUTING.md

@@ -86,40 +86,45 @@ We've made opening one easy by providing a [Pull Request Template](.github/PULL_
 that includes a checklist of things to complete before asking for code review. We look
 forward to reviewing your work! 🙂
 
-
 Developer How-Tos
 -----------------
 
 ### Style Guidelines
 
 We use [Black](https://black.readthedocs.io/en/stable/index.html) and `flake8` to automatically
 lint the code and enforce style requirements as part of the CI pipeline. You can run these style
-tests yourself locally by running `make style` (to check for violations of the `flake8` rules)
-and `make formatcheck` (to see if `black` would reformat the code) in the top-level directory of
+tests yourself locally by running `make check-style` (to check for violations of the `flake8` rules)
+and `make check-format` (to see if `black` would reformat the code) in the top-level directory of
 the repository. If you aren't presented with any errors, then that means your code is good enough
-for the linter (`flake8`) and formatter (`black`). If `make formatcheck` fails, it will present
-you with a diff, which you can resolve by running `make format`.  Black is very opinionated, but
+for the linter (`flake8`) and formatter (`black`). If `make check-format` fails, it will present
+you with a diff, which you can resolve by running `make format`. Black is very opinionated, but
 saves a lot of time by removing the need for style nitpicks in PR review. We only deviate from its
 default behavior in one category: we choose to use a line length of 100 rather than the Black
-default of 88 (this is configured in the [`pyproject.toml`](pyproject.toml) file).
+default of 88 (this is configured in the [`pyproject.toml`](pyproject.toml) file). As for `flake8`,
+we ignore a couple of its rules (all for good reasons), and the specific configuration can be
+found in the [`.flake8`](.flake8) file. We additionally use the [`flake8-bugbear`][bugbear]
+plugin to add a collection of helpful and commonly observed style rules.
 
 In addition to linting and formatting, we are in the process of rolling out the use of type hints
 for all parameters and return values, using the [PEP 484 syntax][pep-484]. This is being done on
-a file-by-file basis, and for ones that have been completed we now have a `make typecheck` command
-that will enforce the use of types in those files as part of the CI. When a file is transitioned,
-it should be added to the list in the `typecheck` target of the [`Makefile`](Makefile). Because we
-use the `typing` module, types (e.g. `type` and `rtype` entries) should be omitted when writing
-(useful) [Sphinx-style](https://sphinx-rtd-tutorial.readthedocs.io/en/latest/docstrings.html)
-docstrings for classes, methods, and functions.
+a file-by-file basis, and for ones that have been completed we now have a `make check-types` command
+that will enforce the use of types in those files as part of the CI, using the popular static
+typechecker [mypy](http://mypy-lang.org/). When a file is transitioned, it should be added to the
+list in the `check-types` target of the [`Makefile`](Makefile). For more information on the specific
+configuration of `mypy` that we use for typechecking, please refer to the [`mypy.ini`](mypy.ini)
+file. Also, because we use the `typing` module, types (e.g. `type` and `rtype` entries) should be
+omitted when writing (useful) [Sphinx-style][sphinx] docstrings for classes, methods, and functions.
 
 As useful shorthand, all of these style-related tests can be run locally with a single command,
 by running the following:
 
 ```bash
-make checkall
+make check-all
 ```
 
+[bugbear]: https://github.com/PyCQA/flake8-bugbear
 [pep-484]: https://www.python.org/dev/peps/pep-0484/
+[sphinx]: https://sphinx-rtd-tutorial.readthedocs.io/en/latest/docstrings.html
 
 ### Running the Unit Tests
 

Makefile

@@ -6,8 +6,21 @@ DOCKER_TAG=rigetti/forest:$(COMMIT_HASH)
 .PHONY: all
 all: dist
 
-.PHONY: checkall
-checkall: formatcheck style typecheck
+.PHONY: check-all
+check-all: check-format check-types check-style
+
+.PHONY: check-format
+check-format:
+	black --check --diff pyquil
+
+# The dream is to one day run mypy on the whole tree. For now, limit checks to known-good files.
+.PHONY: check-types
+check-types:
+	mypy pyquil/quilatom.py pyquil/quilbase.py pyquil/gates.py
+
+.PHONY: check-style
+check-style:
+	flake8
 
 .PHONY: clean
 clean:
@@ -39,10 +52,6 @@ docker: Dockerfile
 format:
 	black pyquil
 
-.PHONY: formatcheck
-formatcheck:
-	black --check --diff pyquil
-
 .PHONY: info
 info:
 	python -V
@@ -56,20 +65,10 @@ install:
 requirements: requirements.txt
 	pip install -r requirements.txt
 
-.PHONY: style
-style:
-	flake8
-
 .PHONY: test
 test:
 	pytest -v --runslow --cov=pyquil
 
-# The dream is to one day run mypy on the whole tree. For now, limit
-# checks to known-good files.
-.PHONY: typecheck
-typecheck:
-	mypy pyquil/quilatom.py pyquil/quilbase.py pyquil/gates.py
-
 .PHONY: upload
 upload:
 	twine upload --repository-url https://test.pypi.org/legacy/ dist/*

examples/1.3_vqe_demo.py

@@ -2,7 +2,6 @@
 This is a demo of VQE through the forest stack. We will do the H2 binding from the Google paper
 using OpenFermion to generate Hamiltonians and Forest to simulate the system
 """
-import sys
 import numpy as np
 import matplotlib.pyplot as plt
 
@@ -18,12 +17,14 @@
 
 from pyquil.quil import Program
 from pyquil.paulis import sX, sY, exponentiate, PauliSum
-from pyquil.gates import X, I
+from pyquil.gates import X
 from pyquil.api import QVMConnection
 from pyquil.unitary_tools import tensor_up
 
 from grove.measurements.estimation import estimate_locally_commuting_operator
 
+QVM_CONNECTION = QVMConnection(endpoint="http://localhost:5000")
+
 
 def get_h2_dimer(bond_length):
     # Set molecule parameters.
@@ -60,7 +61,7 @@ def ucc_circuit(theta):
 
 
 def objective_fun(
-    theta, hamiltonian=None, quantum_resource=QVMConnection(endpoint="http://localhost:5000")
+    theta, hamiltonian=None, quantum_resource=QVM_CONNECTION
 ):
     """
     Evaluate the Hamiltonian bny operator averaging

examples/qaoa_ansatz.py

@@ -26,7 +26,6 @@
 from pyquil.quil import Program
 from pyquil.gates import H
 from pyquil.paulis import sI, sX, sZ, exponentiate_commuting_pauli_sum
-from pyquil.api import QVMConnection
 
 # Create a 4-node array graph: 0-1-2-3.
 graph = [(0, 1), (1, 2), (2, 3)]

examples/website-script.py

@@ -10,7 +10,7 @@
 """
 
 from pyquil import Program, get_qc
-from pyquil.gates import *
+from pyquil.gates import H, CNOT
 
 # construct a Bell State program
 p = Program(H(0), CNOT(0, 1))

pyproject.toml

@@ -17,8 +17,8 @@ exclude = '''
     | build
     | dist
   )/
-  | gen3             # pyquil-specific
-  | external
+  | external         # pyquil-specific
+  | gen3
 
 )
-'''
+'''

pyquil/api/_base_connection.py

@@ -30,7 +30,6 @@
 from pyquil.api._error_reporting import _record_call
 from pyquil.api._errors import error_mapping, UserMessageError, UnknownApiError, TooManyQubitsError
 from pyquil.api._logger import logger
-from pyquil.device import Specs, ISA
 from pyquil.wavefunction import Wavefunction
 
 TYPE_EXPECTATION = "expectation"

pyquil/api/_compiler.py

@@ -34,7 +34,7 @@
 from urllib.parse import urljoin
 
 from pyquil import __version__
-from pyquil.api._base_connection import ForestSession, get_session
+from pyquil.api._base_connection import ForestSession
 from pyquil.api._qac import AbstractCompiler
 from pyquil.api._error_reporting import _record_call
 from pyquil.api._errors import UserMessageError

pyquil/api/_qpu.py

@@ -24,7 +24,7 @@
 
 from pyquil import Program
 from pyquil.parser import parse
-from pyquil.api._base_connection import ForestSession, get_session
+from pyquil.api._base_connection import ForestSession
 from pyquil.api._error_reporting import _record_call
 from pyquil.api._errors import UserMessageError
 from pyquil.api._logger import logger

pyquil/api/_quantum_computer.py

@@ -1199,7 +1199,7 @@ def hadamard(n, dtype=int):
     H = np.array([[1]], dtype=dtype)
 
     # Sylvester's construction
-    for i in range(0, lg2):
+    for _ in range(0, lg2):
         H = np.vstack((np.hstack((H, H)), np.hstack((H, -H))))
 
     return H

pyquil/api/_qvm.py

@@ -34,7 +34,6 @@
 from pyquil.api._config import PyquilConfig
 from pyquil.api._error_reporting import _record_call
 from pyquil.api._qam import QAM
-from pyquil.device import Device
 from pyquil.gates import MOVE, MemoryReference
 from pyquil.noise import apply_noise_model
 from pyquil.paulis import PauliSum

pyquil/api/tests/test_config.py

@@ -1,5 +1,4 @@
 import pytest
-import os
 
 from pyquil.api._config import PyquilConfig
 from pyquil.api._errors import UserMessageError

pyquil/experiment/_memory.py

@@ -20,7 +20,6 @@
 import numpy as np
 
 from pyquil.paulis import PauliTerm
-from pyquil.experiment._symmetrization import SymmetrizationLevel
 
 
 def euler_angles_RX(theta: float) -> Tuple[float, float, float]:

pyquil/experiment/_setting.py

@@ -24,10 +24,6 @@
 from typing import Iterable, Tuple
 
 from pyquil.paulis import PauliTerm, sI, is_identity
-from pyquil.experiment._memory import (
-    pauli_term_to_measurement_memory_map,
-    pauli_term_to_preparation_memory_map,
-)
 
 if sys.version_info < (3, 7):
     from pyquil.external.dataclasses import dataclass