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- import { Observable, of, from, interval, throwError } from 'rxjs';
- import { map, filter, catchError, switchMap, take, tap } from 'rxjs/operators';
- // Mock function to fetch stock prices (simulates API call)
- const fetchStockPrice = (ticker: string): Observable<number> => {
- return new Observable<number>((observer) => {
- const intervalId = setInterval(() => {
- if (Math.random() < 0.1) { // Simulating an error 10% of the time
- observer.error(`Error fetching stock price for ${ticker}`);
- } else {
- const price = parseFloat((Math.random() * 1000).toFixed(2));
- observer.next(price);
- }
- }, 1000);
- return () => {
- clearInterval(intervalId);
- console.log(`Stopped fetching prices for ${ticker}`);
- };
- });
- };
- // Example usage: Tracking stock price updates
- const stockTicker = 'AAPL';
- const stockPrice$ = fetchStockPrice(stockTicker).pipe(
- map(price => ({ ticker: stockTicker, price })), // Transform data
- filter(data => data.price > 500), // Only keep prices above 500
- tap(data => console.log(`Price update:`, data)), // Side effect: Logging
- catchError(err => {
- console.error(err);
- return of({ ticker: stockTicker, price: null }); // Fallback observable
- })
- );
- // Subscribe to the stock price updates
- const subscription = stockPrice$.subscribe({
- next: data => console.log(`Subscriber received:`, data),
- error: err => console.error(`Subscription error:`, err),
- complete: () => console.log('Stream complete'),
- });
- // Automatically unsubscribe after 10 seconds
- setTimeout(() => {
- subscription.unsubscribe();
- console.log('Unsubscribed from stock price updates.');
- }, 10000);
- ---
- class EnforceAttrsMeta(type):
- """
- Metaclass that enforces the presence of specific attributes in a class
- and automatically decorates methods with a logging wrapper.
- """
-
- required_attributes = ['name', 'version']
- def __new__(cls, name, bases, class_dict):
- """
- Create a new class with enforced attributes and method logging.
- :param name: Name of the class being created.
- :param bases: Tuple of base classes.
- :param class_dict: Dictionary of attributes and methods of the class.
- :return: Newly created class object.
- """
- # Ensure required attributes exist
- for attr in cls.required_attributes:
- if attr not in class_dict:
- raise TypeError(f"Class '{name}' is missing required attribute '{attr}'")
- # Wrap all methods in a logging decorator
- for key, value in class_dict.items():
- if callable(value): # Check if it's a method
- class_dict[key] = cls.log_calls(value)
- return super().__new__(cls, name, bases, class_dict)
- @staticmethod
- def log_calls(func):
- """
- Decorator that logs method calls and arguments.
- :param func: Function to be wrapped.
- :return: Wrapped function with logging.
- """
- def wrapper(*args, **kwargs):
- print(f"Calling {func.__name__} with args={args} kwargs={kwargs}")
- result = func(*args, **kwargs)
- print(f"{func.__name__} returned {result}")
- return result
- return wrapper
- class PluginBase(metaclass=EnforceAttrsMeta):
- """
- Base class for plugins that enforces required attributes and logging.
- """
- name = "BasePlugin"
- version = "1.0"
- def run(self, data):
- """
- Process the input data.
- :param data: The data to be processed.
- :return: Processed result.
- """
- return f"Processed {data}"
- class CustomPlugin(PluginBase):
- """
- Custom plugin that extends PluginBase and adheres to enforced rules.
- """
- name = "CustomPlugin"
- version = "2.0"
- def run(self, data):
- """
- Custom processing logic.
- :param data: The data to process.
- :return: Modified data.
- """
- return f"Custom processing of {data}"
- # Uncommenting the following class definition will raise a TypeError
- # because 'version' attribute is missing.
- # class InvalidPlugin(PluginBase):
- # name = "InvalidPlugin"
- if __name__ == "__main__":
- # Instantiate and use the plugin
- plugin = CustomPlugin()
- print(plugin.run("example data"))
- ---
- <!DOCTYPE html>
- <html lang="en">
- <head>
- <meta charset="UTF-8">
- <meta name="viewport" content="width=device-width, initial-scale=1.0">
- <title>Click the Box Game</title>
- <style>
- body {
- text-align: center;
- font-family: Arial, sans-serif;
- }
- #game-container {
- position: relative;
- width: 300px;
- height: 300px;
- margin: 20px auto;
- border: 2px solid black;
- overflow: hidden;
- }
- #target {
- width: 50px;
- height: 50px;
- background-color: red;
- position: absolute;
- cursor: pointer;
- }
- </style>
- </head>
- <body>
- <h1>Click the Box!</h1>
- <p>Score: <span id="score">0</span></p>
- <div id="game-container">
- <div id="target"></div>
- </div>
- <script>
- let score = 0;
- const target = document.getElementById("target");
- const scoreDisplay = document.getElementById("score");
- const container = document.getElementById("game-container");
-
- function moveTarget() {
- const maxX = container.clientWidth - target.clientWidth;
- const maxY = container.clientHeight - target.clientHeight;
- target.style.left = Math.random() * maxX + "px";
- target.style.top = Math.random() * maxY + "px";
- }
-
- target.addEventListener("click", function() {
- score++;
- scoreDisplay.textContent = score;
- moveTarget();
- });
-
- moveTarget();
- </script>
- </body>
- </html>
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