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)