Pythontry嵌套使用技巧与实践方法

try:
    data = read_file('config.json')
    try:
        parsed = json.loads(data)
        try:
            process(parsed)
        except ProcessingError:
            log('Processing failed')
    except json.JSONDecodeError:
        log('Invalid JSON')
except FileNotFoundError:
    log('File not found')

try:
    data = read_file('config.json')
except FileNotFoundError:
    log('File not found')
    return
<p>try:
parsed = json.loads(data)
except json.JSONDecodeError:
log('Invalid JSON')
return</p><p>try:
process(parsed)
except ProcessingError:
log('Processing failed')</p>

def load_config(filename):
    try:
        with open(filename, 'r') as f:
            return json.load(f)
    except FileNotFoundError:
        log(f'{filename} not found')
        raise
    except json.JSONDecodeError as e:
        log(f'Invalid JSON: {e}')
        raise
<p>def run_with_config():
try:
config = load_config('config.json')
process(config)
except (FileNotFoundError, json.JSONDecodeError):</p><h1>外层统一处理配置加载失败</h1><pre class="brush:python;toolbar:false;">    notify_user()
except ProcessingError:
    log('Processing failed')

try:
    conn = database.connect()
    try:
        result = conn.query("SELECT ...")
        cache.set('data', result)
    except CacheError:
        log('Cache write failed, continuing')
    finally:
        conn.close()
except DatabaseError:
    log('Database connection failed')

try:
    file1 = open('a.txt')
    try:
        file2 = open('b.txt')
        # 处理文件
    finally:
        file2.close()
finally:
    file1.close()

with open('a.txt') as f1, open('b.txt') as f2:
    # 处理文件
    pass