Framework design

you-n-g · Jun 20, 2024 · 3334ba9 · 3334ba9
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diff --git a/language/python/design/README.md b/language/python/design/README.md
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+# Introduction
+
+Python的各种设计模式
+- 用linting辅助检测具体设计
+
diff --git a/language/python/design/annot.py b/language/python/design/annot.py
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+# annotations
+
+
+from typing import List, Sequence, Protocol
+
+
+class IA: pass
+class IB(IA): pass
+
+class P(Protocol):
+    def h(self) -> List[IA]: ...
+
+
+class A:
+    def f(self) -> List[IA]:
+        return [IA()]
+
+    def g(self) -> Sequence[IA]:
+        return [IA()]
+
+    def h(self) -> List[IA]:
+        return [IA()]
+
+
+class B(A):
+    def f(self) -> List[IB]:
+        # NOTE: it is a invalid override in linting.
+        return [IB()]
+
+    def g(self) -> Sequence[IB]:
+        # NOTE: it is a valid overriding
+        return [IB()]
+
+    def h(self) -> List[IB]:
+        # NOTE: it is a invalid override in linting.
+        # So protocal does not help here
+        return [IB()]
+
+
+# generic 
+
+from typing import Generic, TypeVar, List
+# Define a type variable
+T = TypeVar('T')
+class Stack(Generic[T]):
+    def __init__(self):
+        self._items: List[T] = []
+    def push(self, item: T) -> None:
+        self._items.append(item)
+    def pop(self) -> T:
+        return self._items.pop()
+    def is_empty(self) -> bool:
+        return len(self._items) == 0
+# Usage
+int_stack = Stack[int]()
+int_stack.push(1)
+int_stack.push(2.)  # NOTE: it is runnable  but does not confirm with linting rules.
+print(int_stack.pop())  # Output: 2.0
+print(int_stack.pop())  # Output: 1
+
+int_stack = Stack() 
+int_stack.push(1)
+int_stack.push(2.) 
+print(int_stack.pop())  # Output: 2.0
+print(int_stack.pop())  # Output: 1
diff --git a/language/python/design/core_frame.py b/language/python/design/core_frame.py
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+"""
+# We'll check the design with `ruff check` &  `mypy`
+
+"""
+from typing import Generic, TypeVar
+
+ASpecificBaseTask = TypeVar("ASpecificBaseTask", bound="BaseTask")
+# Define a type, that refer to a more specific subclass than general `BaseTask`
+
+
+# Core Framework
+class BaseTask:
+    ...
+
+
+class BaseSolver(Generic[ASpecificBaseTask]):
+    """
+    From a semantic perspective,
+    It defines a framework. But it is not designed to handle general BaseTask.
+    Instead, it is designed to handle a specific subclass of BaseTask (But all kinds of specific subclasses can be handled in this class).
+    """
+
+    def g(self, a: ASpecificBaseTask) -> ASpecificBaseTask:
+        return a
+
+
+# concrete framework
+class MTask(BaseTask):
+    ...
+
+
+class MSolver(BaseSolver[MTask]):
+
+    def g(self, a: MTask) -> MTask:
+        """`MSolver.g` only works when a is MTask"""
+        return a
+
+
+ms = MSolver()
+print(isinstance(ms, BaseSolver))  # it will not affect the type checking