feat: python traits

.gitignore

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+*.py[cod]
+*$py.class
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+#Pipfile.lock
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+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
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+#.idea/
+.idea

README.md

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+# PyTraits
+
+## Introduction
+
+PyTraits is a Python library that provides functionality similar to Rust traits. It allows you to define protocols
+using `impl` or `trait` annotations to specify the behavior that classes should implement.
+
+## Installation
+
+You can install PyTraits using pip:
+
+```bash
+pip install pytraits
+```
+
+## Usage
+
+To use PyTraits, first, you need to define a protocol using the `runtime_checkable` annotation:
+
+```python
+from typing import runtime_checkable
+
+
+@runtime_checkable
+class Printable:
+    def print(self):
+        pass
+```
+
+Then, you can use the `impl` annotation to implement the protocol for a class:
+
+
+```python
+from pytraits import impl, trait
+
+
+class MyClass1: pass
+
+
+@impl(Printable)
+class MyClassImplPrintable(MyClass1):
+    def print(self):
+        print("从 MyClass 打印")
+
+
+class MyClass2: pass
+
+
+@trait
+class MyClassTraitPrintable(MyClass2, Printable):
+    def print(self):
+        print("从 MyClass2 打印")
+
+
+mc1: MyClass1 | Printable = MyClass1()
+mc2: MyClass2 | Printable = MyClass2()
+mc1.print()
+mc2.print()
+```
+
+Now, `MyClass` implements the `Printable` protocol and can be used accordingly.
+
+
+## Contributing
+
+Contributions are welcome! If you find any issues or have suggestions for improvement, please open an issue or submit a pull request on GitHub.
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.

README_cn.md

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+# PyTraits
+
+## Introduction
+
+PyTraits is a Python library that provides functionality similar to Rust traits. It allows you to define protocols using `impl` or `trait` annotations to specify the behavior that classes should implement.
+
+## Installation
+
+You can install PyTraits using pip:
+
+```bash
+pip install pytraits
+```
+
+## Usage
+
+
+使用 PyTraits，首先需要使用 `trait` 注解定义一个协议：
+
+```python
+from typing import runtime_checkable
+
+@runtime_checkable
+class Printable:
+    def print(self):
+        pass
+```
+
+然后，可以使用`impl`或`trait`装饰器为已定义的类实现该协议：
+
+```python
+from pytraits import impl, trait
+
+
+class MyClass1: pass
+
+
+@impl(Printable)
+class MyClassImplPrintable(MyClass1):
+    def print(self):
+        print("从 MyClass 打印")
+
+
+class MyClass2: pass
+
+
+@trait
+class MyClassTraitPrintable(MyClass2, Printable):
+    def print(self):
+        print("从 MyClass2 打印")
+
+
+mc1: MyClass1 | Printable = MyClass1()
+mc2: MyClass2 | Printable = MyClass2()
+mc1.print()
+mc2.print()
+```
+
+现在，`MyClass` 实现了 `Printable` 协议，可以相应地使用。
+
+## Contributing
+
+Contributions are welcome! If you find any issues or have suggestions for improvement, please open an issue or submit a pull request on GitHub.
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.

pyproject.toml

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+[project]
+name = "pytraits"
+version = "0.1.0"
+description = "python trait like rust"
+authors = [
+    {name = "JimZhang", email = "zzl22100048@gmail.com"},
+]
+dependencies = []
+requires-python = ">=3.10"
+readme = "README.md"
+license = {text = "MIT"}
+
+[build-system]
+requires = ["pdm-backend"]
+build-backend = "pdm.backend"
+
+
+[tool.pdm]
+distribution = true
+
+
+
+[tool.ruff]
+exclude = [
+    "tests",
+]
+line-length = 120
+select = [
+    "E",
+    "F",
+    "W",
+    "I"
+]
+target-version = "py310"
+[tool.ruff.isort]
+combine-as-imports = true
+
+[tool.pdm.dev-dependencies]
+dev = [
+    "setuptools>=69.0.3",
+]

src/pytraits/__init__.py

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+import inspect
+
+
+class TraitImplementError(RuntimeError):
+    def __init__(self, message):
+        super().__init__(message)
+        self.message = message
+
+
+def check_is_subclass(implementor, protocol):
+    if not issubclass(implementor, protocol):
+        raise TraitImplementError(
+            f'implementor {implementor.__name__} is not a subclass of {protocol.__name__}')
+
+
+def impl(protocol: type):
+    """
+    Decorate a class to make it a trait implementation.
+    :param protocol: Protocol class to be decorated.
+    :return: decorator function
+    """
+
+    def decorator(implementor: type):
+        implemented = implementor.__bases__[0]
+        implementor_methods = []
+        check_is_subclass(implementor, protocol)
+        p_module = protocol.__module__
+        for name, method in inspect.getmembers(protocol, inspect.isfunction):
+            if p_module == method.__module__:
+                implementor_methods.append((name, getattr(implementor, name)))
+        for name, method in implementor_methods:
+            setattr(implemented, name, method)
+
+    return decorator
+
+
+def trait(implementor):
+    """
+    Decorate a class to make it a trait implementation.
+    :param implementor: trait class to be decorated.
+    :return: None. Shadowing subclass
+    """
+    implemented, protocol = implementor.__bases__
+    implementor_methods = []
+    check_is_subclass(implementor, protocol)
+    p_module = protocol.__module__
+    for name, method in inspect.getmembers(protocol, inspect.isfunction):
+        if p_module == method.__module__:
+            implementor_methods.append((name, getattr(implementor, name)))
+    for name, method in implementor_methods:
+        setattr(implemented, name, method)

tests/trait_imple_test.py

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+from typing import Protocol, runtime_checkable
+
+from pytraits import trait, impl
+from traits import ShortUrl
+
+
+class MyUrl:
+    def __init__(self, url):
+        self.url = url
+
+    def url(self):
+        return self.url
+
+
+@trait
+class ShortUrlForMyUrl(MyUrl, ShortUrl):
+
+    def short_url(self):
+        return self.url[0]
+
+
+class Ab:
+    def __init__(self, msg: str):
+        self.msg = msg
+        self.m0 = msg[0]
+
+    def foo(self):
+        print('foo', self.msg)
+
+
+class Abc(Ab):
+    pass
+
+
+@runtime_checkable
+class BProtocol(Protocol):
+    def print_m0(self):
+        pass
+
+
+@runtime_checkable
+class DProtocol(Protocol):
+    def print_1(self):
+        pass
+
+
+@impl(BProtocol)
+class C(Abc):
+
+    def print_m0(self):
+        print('show', self.m0)
+
+
+@trait
+class D(Abc, DProtocol):
+    def print_1(self):
+        print('show', self.m0)
+        self.foo()
+
+
+if __name__ == '__main__':
+    a: Ab | DProtocol = Abc('acb')
+    a.print_1()
+    my_url: MyUrl | ShortUrl = MyUrl('http://acb.com')
+    print(my_url.short_url())

tests/traits.py

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+from typing import Protocol, runtime_checkable
+
+
+@runtime_checkable
+class ShortUrl(Protocol):
+    def short_url(self):
+        ...