🔧 Adding

Mediator Pattern

Author: raj713335

06 Behavioral Design Patterns/04 Mediator Design Pattern.py

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+from abc import ABC, abstractmethod
+
+
+# -------------------- Mediator Interface --------------------
+class Mediator(ABC):
+    @abstractmethod
+    def notify(self, sender: object, event: str):
+        pass
+
+
+# -------------------- Base Component --------------------
+class Component:
+    def __init__(self, mediator: Mediator = None):
+        self._mediator = mediator
+
+    def set_mediator(self, mediator: Mediator):
+        self._mediator = mediator
+
+
+# -------------------- Concrete Components --------------------
+class Button(Component):
+    def click(self):
+        print("[Button Clicked]")
+        self._mediator.notify(self, "click")
+
+
+class Checkbox(Component):
+    def __init__(self, mediator=None):
+        super().__init__(mediator)
+        self.checked = False
+
+    def toggle(self):
+        self.checked = not self.checked
+        print(f"[Checkbox Toggled] checked = {self.checked}")
+        self._mediator.notify(self, "check")
+
+
+class Textbox(Component):
+    def __init__(self, mediator=None):
+        super().__init__(mediator)
+        self.visible = True
+        self.content = ""
+
+    def set_visible(self, visible: bool):
+        self.visible = visible
+        print(f"[Textbox] {'Shown' if visible else 'Hidden'}")
+
+    def set_content(self, content: str):
+        self.content = content
+
+
+# -------------------- Concrete Mediator --------------------
+class AuthenticationDialog(Mediator):
+    def __init__(self):
+        # Components
+        self.title = "Dialog"
+        self.login_checkbox = Checkbox(self)
+        self.username_login = Textbox(self)
+        self.password_login = Textbox(self)
+
+        self.username_register = Textbox(self)
+        self.password_register = Textbox(self)
+        self.email_register = Textbox(self)
+
+        self.ok_button = Button(self)
+        self.cancel_button = Button(self)
+
+        self.set_initial_state()
+
+    def set_initial_state(self):
+        self.title = "Login"
+        self.username_login.set_visible(True)
+        self.password_login.set_visible(True)
+
+        self.username_register.set_visible(False)
+        self.password_register.set_visible(False)
+        self.email_register.set_visible(False)
+
+    def notify(self, sender: object, event: str):
+        if sender == self.login_checkbox and event == "check":
+            if self.login_checkbox.checked:
+                self.title = "Login"
+                print("\n[Dialog switched to Login mode]")
+                self.username_login.set_visible(True)
+                self.password_login.set_visible(True)
+                self.username_register.set_visible(False)
+                self.password_register.set_visible(False)
+                self.email_register.set_visible(False)
+            else:
+                self.title = "Register"
+                print("\n[Dialog switched to Registration mode]")
+                self.username_login.set_visible(False)
+                self.password_login.set_visible(False)
+                self.username_register.set_visible(True)
+                self.password_register.set_visible(True)
+                self.email_register.set_visible(True)
+
+        elif sender == self.ok_button and event == "click":
+            if self.login_checkbox.checked:
+                print("\n[Logging in user...]")
+                # In real code, validate login form
+                if not self.username_login.content or not self.password_login.content:
+                    print("Login failed: Missing username or password.")
+                else:
+                    print(f"Login success for user: {self.username_login.content}")
+            else:
+                print("\n[Registering new user...]")
+                # In real code, validate registration form
+                if not self.username_register.content or not self.password_register.content or not self.email_register.content:
+                    print("Registration failed: Missing fields.")
+                else:
+                    print(f"User {self.username_register.content} registered with email {self.email_register.content}.")
+
+
+# -------------------- Application (Client Code) --------------------
+def main():
+    dialog = AuthenticationDialog()
+
+    # Toggle between login and register
+    dialog.login_checkbox.toggle()  # Switch to Login
+    dialog.username_login.set_content("john_doe")
+    dialog.password_login.set_content("123456")
+    dialog.ok_button.click()
+
+    print("\n---\n")
+
+    dialog.login_checkbox.toggle()  # Switch to Register
+    dialog.username_register.set_content("jane_doe")
+    dialog.password_register.set_content("abcdef")
+    dialog.email_register.set_content("jane@example.com")
+    dialog.ok_button.click()
+
+
+if __name__ == "__main__":
+    main()