25th November 2022

Coding⚑

Languages⚑

PDM⚑

• Correction: Solve circular dependencies by manual constraining.

  It also helps to run pdm update with the -v flag, that way you see which are the candidates that are rejected, and you can put the constrain you want. For example, I was seeing the next traceback:

  pdm.termui: Conflicts detected:
    pyflakes>=3.0.0 (from <Candidate autoflake 2.0.0 from https://pypi.org/simple/autoflake/>)
    pyflakes<2.5.0,>=2.4.0 (from <Candidate flake8 4.0.1 from unknown>)
  

  So I added a new dependency to pin it:

  [tool.pdm.dev-dependencies]
  dependencies = [
      # Until flakeheaven supports flake8 5.x
      # https://github.com/flakeheaven/flakeheaven/issues/132
      "flake8>=4.0.1,<5.0.0",
      "pyflakes<2.5.0",
  ]
  

  If none of the above works, you can override them:

  [tool.pdm.overrides]
  "importlib-metadata" = ">=3.10"
  

Click⚑

• New: File System Isolation.

  For basic command line tools with file system operations, the CliRunner.isolated_filesystem() method is useful for setting the current working directory to a new, empty folder.

  from click.testing import CliRunner
  from cat import cat
  
  def test_cat():
      runner = CliRunner()
      with runner.isolated_filesystem():
          with open("hello.txt", "w") as f:
              f.write("Hello World!")
  
          result = runner.invoke(cat, ["hello.txt"])
          assert result.exit_code == 0
          assert result.output == "Hello World!\n"
  

  Pass temp_dir to control where the temporary directory is created. The directory will not be removed by Click in this case. This is useful to integrate with a framework like Pytest that manages temporary files.

  def test_keep_dir(tmp_path):
      runner = CliRunner()
  
      with runner.isolated_filesystem(temp_dir=tmp_path) as td:
          ...
  

Python Snippets⚑

• New: Pathlib make parent directories if they don't exist.

  pathlib.Path("/tmp/sub1/sub2").mkdir(parents=True, exist_ok=True)
  

  From the docs:

  • If parents is true, any missing parents of this path are created as needed; they are created with the default permissions without taking mode into account (mimicking the POSIX mkdir -p command).

  • If parents is false (the default), a missing parent raises FileNotFoundError.

  • If exist_ok is false (the default), FileExistsError is raised if the target directory already exists.

  • If exist_ok is true, FileExistsError exceptions will be ignored (same behavior as the POSIX mkdir -p command), but only if the last path component is not an existing non-directory file.

• New: Pathlib touch a file.

  Create a file at this given path.

  pathlib.Path("/tmp/file.txt").touch(exist_ok=True)
  

  If the file already exists, the function succeeds if exist_ok is true (and its modification time is updated to the current time), otherwise FileExistsError is raised.

  If the parent directory doesn't exist you need to create it first.

  python global_conf_path = xdg_home / "autoimport" / "config.toml" global_conf_path.parent.mkdir(parents=True) global_conf_path.touch(exist_ok=True)