WPS237 Found a too complex f string - this may be too strict

[Andrew-Sheridan]

What's wrong

The following line raises WPS237

self.info(f"Count={count:,}")

  37:19    WPS237 Found a too complex `f` string
  self.info(f"Count={count:,}")

How it should be

It should not do that, as that does not seem an overly complex f-string.

It is formatting an int as a comma separated value: f"count={count:,}" -> "count=1,234"

• this is the same as "count={count:,}".format(count=count)

Flake8 version and plugins

{
  "dependencies": [],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.7.3",
    "system": "Darwin"
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      "plugin": "flake8-darglint",
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      "is_local": false,
      "plugin": "flake8-debugger",
      "version": "4.0.0"
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      "is_local": false,
      "plugin": "flake8-docstrings",
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      "plugin": "flake8-eradicate",
      "version": "1.0.0"
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    {
      "is_local": false,
      "plugin": "flake8-string-format",
      "version": "0.3.0"
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    {
      "is_local": false,
      "plugin": "flake8_commas",
      "version": "2.0.0"
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    {
      "is_local": false,
      "plugin": "flake8_isort",
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      "plugin": "naming",
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pip information

pip 21.0.1

cannot show pip freeze

OS information

macOS Catalina 10.15.7 (19H114

[vnmabus]

I also have a problem with the strictness of this rule regarding len. Somehow f"The length is {len(l)}." is considered a too complex f-string.

[sobolevn]

These two are different:

• Original problem by @Andrew-Sheridan is about formatting, it should be allowed
• Problem @vnmabus is about putting logic into f strings, it won't be ever allowed. We even made an exceptional rule for people who like to use them (still wps does not recommend it), but prefer to keep them as simple as referencing variables. So, that's the only use-case we support

I am going to fix the first one in 0.15.3, I am working on it right now. 👋

[sobolevn]

Ok, I was wrong 🙂 Sorry, I am not using f string, so I forgot about it.

We do allow some simple expressions: and yes, len(a) is not allowed because of this code:

# Function call with empty arguments is okay
        elif isinstance(format_value, ast.Call) and not format_value.args:
            return True