2025-09-10:仓库迁移

8.类与对象/11.简化数据结构的初始化过程.py

@@ -0,0 +1,59 @@
+# 有时候你编写了一堆类当数据结构用,但是懒得写一堆init函数,这时候可以将初始化数据结构的init函数归纳到一个公共基类中
+
+class Structure:
+    _fields = []
+    def __init__(self, *args, **kwargs):
+        if len(args) > len(self._fields):
+            raise TypeError("Expect {} arguments, but only {}".format(len(self._fields), len(args)))
+
+        # 处理顺序输入的参数
+        for name, value in zip(self._fields, args):
+            setattr(self, name, value)
+
+        # 处理关键字参数
+        for name in args[len(self._fields):]:
+            setattr(self, name, kwargs.pop(name))
+
+        # 处理多余的关键字参数
+        if kwargs:
+            raise TypeError("Invalid arguments {}".format(",".join(kwargs)))
+
+
+class lazy:
+    def __init__(self, func):
+        self.func = func
+
+    def __get__(self, instance, cls):
+        if instance is None:
+            return self
+        else:
+            value = self.func(instance)
+            setattr(instance, self.func.__name__, value)
+            return value
+
+# 这时候我们会发现你只需要指定参数就行了,异常的好使
+import math
+if __name__ == '__main__':
+
+    class Stock(Structure):
+        _fields = ["name", "shares", "price"]
+        __slots__ = _fields
+
+    class Points(Structure):
+        _fields = ["x", "y"]
+        __slots__ = _fields
+
+
+    class Circle(Structure):
+        _fields = ["radius"]
+        __slots__ = _fields
+        @lazy
+        def area(self):
+            return math.pi * self.radius ** 2
+
+    s = Stock('ACME', 50, 91.1)
+    p = Points(2,3)
+    c = Circle(4.5)
+    print(c.area)
+    print(c.area)
+