Add formatter module

[denisart]

1. Added a new formatter module (now is not using in main code).

Example:

from datamodel_code_generator.formatter.base import BaseCodeFormatter

class CustomHeaderCodeFormatter(BaseCodeFormatter):
        formatter_name: ClassVar[str] = "custom"

        def __init__(self, formatter_kwargs: Dict[str, Any]) -> None:
            super().__init__(formatter_kwargs=formatter_kwargs)
            default_header = "my header"
            self.header: str = self.formatter_kwargs.get("header", default_header)

        def apply(self, code: str) -> str:
            return f'# {self.header}\\n{code}'
        
formatter_kwargs = {"header": "formatted with CustomHeaderCodeFormatter"}
formatter = CustomHeaderCodeFormatter(formatter_kwargs)

code = '''x = 1\ny = 2'''
print(formatter.apply(code))
"""
# formatted with CustomHeaderCodeFormatter
x = 1
y = 2
"""

2. Added isort, black and ruff (empty now) formatters based on datamodel_code_generator.formatter.base.BaseCodeFormatter.

3. New formatters runner (based on CodeFormatter from datamodel_code_generator.format). Usage example:

runner = CodeFormattersRunner(
    default_formatter=['black', 'isort'],
    disable_default_formatter=False,
    custom_formatters=["my_package.my_sub_package.CustomHeaderCodeFormatter"],
    custom_formatters_kwargs={
        'custom': {
            'header': 'formatted with CustomHeaderCodeFormatter',
        }
    }
)

runner.format_code("...")
# running black
# running isort
# running custom

[codspeed-hq]

CodSpeed Performance Report

Merging #1746 will not alter performance

_{Comparing denisart:add-formatter-module (c33815c) with main (f856d13)}

Summary

✅ 31 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 21 lines in your changes missing coverage. Please review.

Project coverage is 99.51%. Comparing base (f856d13) to head (c33815c).

Files	Patch %	Lines
datamodel_code_generator/formatter/base.py	87.93%	6 Missing and 1 partial ⚠️
datamodel_code_generator/formatter/black.py	78.78%	4 Missing and 3 partials ⚠️
datamodel_code_generator/formatter/isort.py	73.91%	4 Missing and 2 partials ⚠️
datamodel_code_generator/formatter/ruff.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main    #1746      +/-   ##
===========================================
- Coverage   100.00%   99.51%   -0.49%     
===========================================
  Files           38       43       +5     
  Lines         4212     4338     +126     
  Branches       973      992      +19     
===========================================
+ Hits          4212     4317     +105     
- Misses           0       15      +15     
- Partials         0        6       +6     

Flag	Coverage Δ
unittests	99.14% <81.74%> (-0.53%)	⬇️

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[denisart]

Log from single failed test:

ChefBuildError

  Backend 'setuptools.build_meta:__legacy__' is not available.

  at ~\.local\venv\Lib\site-packages\poetry\installation\chef.py:152 in _prepare
      148| 
      149|                 error = ChefBuildError("\n\n".join(message_parts))
      150| 
      151|             if error is not None:
    > 152|                 raise error from None
      153| 
      154|             return path
      155| 
      156|     def _prepare_sdist(self, archive: Path, destination: Path | None = None) -> Path:

Note: This error originates from the build backend, and is likely not a problem with poetry but with lazy-object-proxy (1.9.0) not supporting PEP 517 builds. You can verify this by running 'pip wheel --use-pep517 "lazy-object-proxy (==1.9.0)"'.

[koxudaxi]

@denisart could you please rebase the branch?
I just updated the poetry version and merged it to main.

[koxudaxi]

@denisart the best is that you add the write permission of the PR to me

[koxudaxi]

@denisart
Thank you for the great PR.
I left a few comments.

[koxudaxi]

I didn't think the uses case 😅

[denisart]

I also had the same reaction. But the Import class is very suitable in this case.

[koxudaxi]

Why does the method expect the path string?
I prefer custom_formatter: BaseCodeFormatter to raw str.
We can use type-checking.

If we want to pass the custom formatted class from CLI, how about loading the custom formatted class from str only for that?
I feel that passing raw str is a bit confusing, since it is also intended to be used as a module by the user.

[denisart]

It seems I didn't fully understand your proposal. Can you explain or give an example?

[koxudaxi]

@denisart
I'm sorry I show you the code.
I expect the arguments.

class CodeFormattersRunner:
    ...
    def __init__(
        self,
        disable_default_formatter: bool = False,
        default_formatter: Optional[List[BaseCodeFormatter]] = None,
        custom_formatters: Optional[List[BaseCodeFormatter]] = None,

if we give the external formatter to CodeFormattersRunner, we should get the BaseCodeFormatter by using
load_code_formatter

custom_comatter = load_code_formatter("my_package.my_sub_package.FormatterName")
runner = CodeFormattersRunner(custom_formatters=[custom_comatter])

I don't think CodeFormattersRunner must know the full path string; CodeFormattersRunner only needs to handle the CodeFormatter class. What do you think?

[denisart]

@koxudaxi ,
I understood your idea. Do you propose to move the loading of formatters from CodeFormattersRunner? This is good from an architectural point of view.

Do you propose loading formatters by path in generate method from datamodel_code_generator/__init__.py?

[koxudaxi]

@denisart

I understood your idea. Do you propose to move the loading of formatters from CodeFormattersRunner? This is good from an architectural point of view.

Yes!!

Do you propose loading formatters by path in generate method from datamodel_code_generator/init.py?

Yes, it is. Thank you for saying what I was trying to say.

[denisart]

Okay, I agree with you. I'll create a fix.