Add Visitor Pattern

Author: ELC

patterns/behavioural/visitor/problem_01/__init__.py

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+from .algorithm import Algorithm
+from .print import Print
+
+__all__ = ["Algorithm", "Print"]

patterns/behavioural/visitor/problem_01/algorithms/__init__.py

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+from typing import Protocol
+
+from ..files import SealedFileType
+
+
+class Algorithm(Protocol):
+    def visit(self, element: SealedFileType) -> None:
+        ...

patterns/behavioural/visitor/problem_01/algorithms/algorithm.py

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+from ..files import SealedFileType, Audio, Text, Image
+
+from typing import TypeVar, Generic
+
+T = TypeVar("T", bound=SealedFileType)
+
+
+class Print(Generic[T]):
+    def visit(self, element: T) -> None:
+        if isinstance(element, Audio):
+            PrintAudio().visit(element)
+            return
+        elif isinstance(element, Text):
+            PrintText().visit(element)
+            return
+
+        PrintImage().visit(element)
+
+
+class PrintAudio(Print[Audio]):
+    def visit(self, element: Audio) -> None:
+        print(f"{element.codec=}")
+
+
+class PrintText(Print[Text]):
+    def visit(self, element: Text) -> None:
+        print(f"{element.encoding=}")
+
+
+class PrintImage(Print[Image]):
+    def visit(self, element: Image) -> None:
+        print(f"{element.width=}, {element.height=}")

patterns/behavioural/visitor/problem_01/algorithms/print.py

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+from .audio import Audio
+from .text import Text
+from .image import Image
+
+from typing import Union
+
+SealedFileType = Union[Audio, Text, Image]
+
+__all__ = ["Audio", "Text", "Image", "SealedFileType"]

patterns/behavioural/visitor/problem_01/files/__init__.py

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+from dataclasses import dataclass
+from .filetype import FileType
+
+
+@dataclass
+class Audio(FileType):
+    codec: str = "mp4"

patterns/behavioural/visitor/problem_01/files/audio.py

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+from abc import ABC
+
+from dataclasses import dataclass
+
+
+@dataclass
+class FileType(ABC):
+    name: str = "asdf"

patterns/behavioural/visitor/problem_01/files/filetype.py

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+from dataclasses import dataclass
+from .filetype import FileType
+
+
+@dataclass
+class Image(FileType):
+    height: float = 1080
+    width: float = 1920

patterns/behavioural/visitor/problem_01/files/image.py

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+from dataclasses import dataclass
+from .filetype import FileType
+
+
+@dataclass
+class Text(FileType):
+    encoding: str = "utf-8"