Migrate to f-strings

[StrikerRUS]

m2cgen's codebase heavily utilizes string formatting and concatenation mechanisms. f-strings (brief guide) are known to be the fastest method to format string (1, 2) and they increase code readability a lot.

Source: https://cito.github.io/blog/f-strings/.

One problem is only that they are supported starting from Python 3.6, but currently m2cgen supports Python 3.5.

m2cgen/setup.py

Line 28 in 7626a60

"Programming Language :: Python :: 3.5",

My suggestion is the following. Mark the next 0.8.0 release as the latest which supports Python 3.5 and drop the support in 0.9.0 release. It will be approximately in the same time as Python 3.5 reaches its EOL (2020-09-13).

[StrikerRUS]

OK, as we've agreed to drop Python 3.5 after 0.8.0 release, I'd like to list all files in the project that should be checked for replacing format to f-string. It will be useful because I don't think that one huge PR is a good idea. Instead, a bunch of small PRs is better in terms of review speed and ease.

• m2cgen\setup.py
• m2cgen\generated_code_examples\python\classification\decision_tree.py
• m2cgen\generated_code_examples\python\classification\lightgbm.py
• m2cgen\generated_code_examples\python\classification\linear.py
• m2cgen\generated_code_examples\python\classification\random_forest.py
• m2cgen\generated_code_examples\python\classification\svm.py
• m2cgen\generated_code_examples\python\classification\xgboost.py
• m2cgen\generated_code_examples\python\regression\decision_tree.py
• m2cgen\generated_code_examples\python\regression\lightgbm.py
• m2cgen\generated_code_examples\python\regression\linear.py
• m2cgen\generated_code_examples\python\regression\random_forest.py
• m2cgen\generated_code_examples\python\regression\svm.py
• m2cgen\generated_code_examples\python\regression\xgboost.py
• m2cgen\m2cgen\ast.py
• m2cgen\m2cgen\cli.py
• m2cgen\m2cgen\exporters.py
• m2cgen\m2cgen_init_.py
• m2cgen\m2cgen_main_.py
• m2cgen\m2cgen\assemblers\base.py
• m2cgen\m2cgen\assemblers\boosting.py
• m2cgen\m2cgen\assemblers\ensemble.py
• m2cgen\m2cgen\assemblers\fallback_expressions.py
• m2cgen\m2cgen\assemblers\linear.py
• m2cgen\m2cgen\assemblers\meta.py
• m2cgen\m2cgen\assemblers\svm.py
• m2cgen\m2cgen\assemblers\tree.py
• m2cgen\m2cgen\assemblers\utils.py
• m2cgen\m2cgen\assemblers_init_.py
• m2cgen\m2cgen\interpreters\code_generator.py
• m2cgen\m2cgen\interpreters\interpreter.py
• m2cgen\m2cgen\interpreters\mixins.py
• m2cgen\m2cgen\interpreters\utils.py
• m2cgen\m2cgen\interpreters_init_.py
• m2cgen\m2cgen\interpreters\c\code_generator.py
• m2cgen\m2cgen\interpreters\c\interpreter.py
• m2cgen\m2cgen\interpreters\c_init_.py
• m2cgen\m2cgen\interpreters\c_sharp\code_generator.py
• m2cgen\m2cgen\interpreters\c_sharp\interpreter.py
• m2cgen\m2cgen\interpreters\c_sharp_init_.py
• m2cgen\m2cgen\interpreters\dart\code_generator.py
• m2cgen\m2cgen\interpreters\dart\interpreter.py
• m2cgen\m2cgen\interpreters\dart_init_.py
• m2cgen\m2cgen\interpreters\go\code_generator.py
• m2cgen\m2cgen\interpreters\go\interpreter.py
• m2cgen\m2cgen\interpreters\go_init_.py
• m2cgen\m2cgen\interpreters\haskell\code_generator.py
• m2cgen\m2cgen\interpreters\haskell\interpreter.py
• m2cgen\m2cgen\interpreters\haskell_init_.py
• m2cgen\m2cgen\interpreters\java\code_generator.py
• m2cgen\m2cgen\interpreters\java\interpreter.py
• m2cgen\m2cgen\interpreters\java_init_.py
• m2cgen\m2cgen\interpreters\javascript\code_generator.py
• m2cgen\m2cgen\interpreters\javascript\interpreter.py
• m2cgen\m2cgen\interpreters\javascript_init_.py
• m2cgen\m2cgen\interpreters\php\code_generator.py
• m2cgen\m2cgen\interpreters\php\interpreter.py
• m2cgen\m2cgen\interpreters\php_init_.py
• m2cgen\m2cgen\interpreters\powershell\code_generator.py
• m2cgen\m2cgen\interpreters\powershell\interpreter.py
• m2cgen\m2cgen\interpreters\powershell_init_.py
• m2cgen\m2cgen\interpreters\python\code_generator.py
• m2cgen\m2cgen\interpreters\python\interpreter.py
• m2cgen\m2cgen\interpreters\python\linear_algebra.py
• m2cgen\m2cgen\interpreters\python_init_.py
• m2cgen\m2cgen\interpreters\r\code_generator.py
• m2cgen\m2cgen\interpreters\r\interpreter.py
• m2cgen\m2cgen\interpreters\r_init_.py
• m2cgen\m2cgen\interpreters\ruby\code_generator.py
• m2cgen\m2cgen\interpreters\ruby\interpreter.py
• m2cgen\m2cgen\interpreters\ruby_init_.py
• m2cgen\m2cgen\interpreters\visual_basic\code_generator.py
• m2cgen\m2cgen\interpreters\visual_basic\interpreter.py
• m2cgen\m2cgen\interpreters\visual_basic_init_.py
• m2cgen\tests\conftest.py
• m2cgen\tests\test_ast.py
• m2cgen\tests\test_cli.py
• m2cgen\tests\test_fallback_expressions.py
• m2cgen\tests\utils.py
• m2cgen\tests_init_.py
• m2cgen\tests\assemblers\test_ensemble.py
• m2cgen\tests\assemblers\test_lightgbm.py
• m2cgen\tests\assemblers\test_linear.py
• m2cgen\tests\assemblers\test_meta.py
• m2cgen\tests\assemblers\test_svm.py
• m2cgen\tests\assemblers\test_tree.py
• m2cgen\tests\assemblers\test_xgboost.py
• m2cgen\tests\assemblers_init_.py
• m2cgen\tests\e2e\test_cli.py
• m2cgen\tests\e2e\test_e2e.py
• m2cgen\tests\e2e_init_.py
• m2cgen\tests\e2e\executors\base.py
• m2cgen\tests\e2e\executors\c.py
• m2cgen\tests\e2e\executors\c_sharp.py
• m2cgen\tests\e2e\executors\dart.py
• m2cgen\tests\e2e\executors\go.py
• m2cgen\tests\e2e\executors\haskell.py
• m2cgen\tests\e2e\executors\java.py
• m2cgen\tests\e2e\executors\javascript.py
• m2cgen\tests\e2e\executors\php.py
• m2cgen\tests\e2e\executors\powershell.py
• m2cgen\tests\e2e\executors\python.py
• m2cgen\tests\e2e\executors\r.py
• m2cgen\tests\e2e\executors\ruby.py
• m2cgen\tests\e2e\executors\visual_basic.py
• m2cgen\tests\e2e\executors_init_.py
• m2cgen\tests\interpreters\test_c.py
• m2cgen\tests\interpreters\test_c_sharp.py
• m2cgen\tests\interpreters\test_dart.py
• m2cgen\tests\interpreters\test_go.py
• m2cgen\tests\interpreters\test_haskell.py
• m2cgen\tests\interpreters\test_java.py
• m2cgen\tests\interpreters\test_javascript.py
• m2cgen\tests\interpreters\test_php.py
• m2cgen\tests\interpreters\test_powershell.py
• m2cgen\tests\interpreters\test_python.py
• m2cgen\tests\interpreters\test_r.py
• m2cgen\tests\interpreters\test_ruby.py
• m2cgen\tests\interpreters\test_visual_basic.py
• m2cgen\tests\interpreters_init_.py
• m2cgen\tools\generate_code_examples.py
• m2cgen\tools_init_.py

[StrikerRUS]

Closed via #248 and #254.