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透過手動修改函數的實作來更改函數的行為是顯而易見的,但是我們可以在應用程式運行時以某種方式搞亂函數的實作嗎?讓我們將這個過程分為 3 個步驟:
我們先來學習如何取得函數的原始碼:
# Import inspect module import inspect # Define some callback function def function(): print('Do something') source_code = inspect.getsource(function) print(source_code)
輸出:
def callback(): print('Do something')
現在讓我們看看如何將字串中提供的任意 Python 程式碼轉換為可呼叫的 Python 物件:
# Source code that we want to execute source_code = 'print("Hello from the inside of the string!")' # Wrap the source code into a function definition, so that it can be accessed by name function_name = 'print_hello' function_definition = f'def {function_name}():\n {source_code}' namespace = {} # Execute code with a function definition within the given namespace, so that the function definition is created exec(function_definition, namespace) # Retrieve function from the namespace and save to a callable variable print_hello = namespace[function_name] # Call the function print_hello()
輸出:
Hello from the inside of the string!
現在讓我們實作一個函數,它將函數指標作為輸入並傳回一個帶有修改後的原始程式碼的可呼叫物件:
import inspect def get_hacked_function(function): # Get the source code of the given function original_function_source_code = inspect.getsource(function) # Append a new line to the function source code modified_function_source_code = f'{original_function_source_code} print("You didn\'t expect me here!")' # Call the function within the namespace namespace = {} exec(modified_function_source_code, namespace) # Parse function name by taking everything what's between "def " and "(" at the first line function_name = original_function_source_code.split('(')[0].split()[1] # Retrieve modified function modified_function = namespace[function_name] # Return modified function return modified_function
是時候測試一下了!
# This is the function passed as an input def original_function(): print("Hello") # Call our hacking function hacked_function = get_hacked_function(original_function) # Call the modified function hacked_function()
輸出:
Hello You didn't expect me here!
初學者註意事項:請記住,此類實驗主要用於教育目的。使用 exec() 函數會帶來嚴重的安全性問題,因此不建議在生產環境中使用它。如果您需要修改您無法存取其原始程式碼的函數的行為,請考慮使用函數裝飾器。在使用 exec() 之前始終保持謹慎並確保您完全理解安全隱患。
以上是透過更改原始碼來破解 Python 函數的詳細內容。更多資訊請關注PHP中文網其他相關文章!